Some further updates for anyone interested in the outboard idea:
I was able to personally make contact with one of the BC Albineers who ran a kicker on his Albin 25. According to him, he mounted a modern 9.9 Yamaha high thrust (117lbs) on the transom in a split swim platform configuration using an Adventure Marine kicker bracket. He bolted it directly to the hull, using only a metal backing plate. He configured the outboard to run remotely via a troll-ez steering rig. His engine had power tilt and trim & start. According to him he got 9 knots from his 35hp diesel. He got 7 knots using the 9.9 yamaha kicker. He thought his fuel consumption ran 1 - 1.5 gallon per hour with the outboard.

Based off his experiences, he thought the idea of using a outboard as a primary was not a bad one. He questioned whether a 25hp would even be necessary, feeling 15hp would be just right. Unfortunately they don't make a 15hp high thrust. The 25hp puts out 13amps, and can swing a 14" prop and weights 203 lbs.
Although Don and I spar back and forth flogging the same horse, I want to respond to some of the larger arguments. His arguments are an excellent devils advocate. I think some of the arguments against the outboard are better than others which is why I haven't pulled the trigger yet.
Re: the Transom strength.Comparing the A25 to the A27 makes me think its not a problem to mount a 25hp on the transom. Clearly it would provide more power than the 9.9hp. Yes it weighs more, but trasom supports 2-3 adults or a dingy on the swim platfrom as is, much more than 203lbs. The forces of pushing the boat at displacement speed just does not seem the same as a skiff going 20mph on plane.
For arguments sake, is the fear that the transom would somehow fail? If it did what would that look like? Perhaps crushing of the transom core or cracking of the fiberglass sheathing. You'd see spider cracks around the mount points? Or maybe the motor mount would break free from the boat transom and rip a gaping hole? Remember this is 6.5 knots we're cruising at. This is a function of distributing a load over an area, perhaps improving the core at the mount points, amply solved by a backing plate & reinforcement of some sort. The backing plate has to be bigger than the motor mount points, and the motor mount has to dispurse the weight over an area on the transom, so it might be mitigated by a mount design. Is the fear that the transom would separate from the hull sides? I could see this at planning speeds breaking through chop I suppose. But at 6.5 knots, you'd more likely see flex between the transom and hull sides if anything. But there's rigidity from the liner too. Knees fiberglassed into the sides would help this, if even necessary, as I have seen it done on other boats.
Re: the Resale argument. I hear this argument alot. IMO When someone uses this argument, what they are really saying is "I wouldn't buy that boat." But that has no effect on the actual re-sale ability of the boat. For example, I wouldn't buy an A27 with a repowered 100hp Yanmar. I couldnt afford it at what you'd have to ask. That doesn't mean your boat will be less likely to sell--lots of people want a repowered A27. Me personally, I cant afford it. You have affected your re-sale ability the same as I will. Which is to say, someone will buy your boat. Just not me.
That resale argument never had much value to me. In so far as being concerned that someone won't "like my boat" or "want what I have" I never put much stock. I want what I want. You want want what you want. God knows I don't buy boats to make money. And no matter how much I fool myself not one of my boats ever turned out to be an actual investment--financially. I don't want to loose my shirt owning a boat. Which means I probably sell it for what I paid, or maybe a little more if I made a significant improvement.
To me if someone wants an Albin 27, there's not 500 of them for sale at any one time, because there were approx 500 max ever made. This is a very niche boat serving a very particular customer. They're not buying an Albin 25/27 for the sake of the Albin name so much as what it is and is capable of. There's really nothing like it. If you want a purist A27, there's like 3-4 at any one time depending on the season--and thats nationwide. Generally speaking, they are all exactly the same, just better stages of TLC. Not a single A27 that I could find in the past year has been offered with an upgraded, repowered diesel figured proportionally into the price. A25's are very similar. Alot of A25/A27's aren't even offered with a trailer. The truth of the matter is A27's are selling for somewhere between $10k to $18k, with most being listed at $22-28k---but no one is actually paying that price. Take a look. The same boats at the same price have been listed by brokerages for 12+ months at that price point. They are going nowhere. Thats price affecting re-sale ability. We shouldn't fool ourselves into thinking the A27 actually sells for $25-$30k. We also shouldnt fool ourselves into thinking it's max value in best restored condition is more than $30k.
That means if you repower your A27, costing $14k, you will never recoup that full cost in any way shape or form--unless you got the boat FREE, other than by your own use and the pleasure you get from it. Thats not a bad reason to pay for the repower, and I'm wrestling with it myself. But it does highlight the "true Resale Arguement."
The true resale arguement is that people want A27s, any A27s, in any condition, with or without a trailer, old engine or new, gas or diesel, because there's not that many and there never will be. Its unique in its design and member following. Its one of literally a handful of efficient pocket displacement trawlers in the downeast style, with the aft cabin, hardtop, standing head and galley. You cant buy the same thing today and not pay $100k or more. People only pay a fixed price for them. And no one is getting $30k for their 30 year old A27 repowered with a diesel. Just check our classifieds. Every single A27 owner, who has not found a suitable repower option, has the same issue. Great boat with a 30 year old (quite possibly hard to find parts) diesel engine. Your diesel goes sideways one day--guess what your only option is a $15k investment just to have a boat that can leave the dock? Any number of odd maintenance issues (rusting exhaust elbows, pumps, gaskets, whatever) and you are now searching for elusive rarer-than-gold parts. Oh and you have to be able to work on it. Or ask the three other people in the group who have the same weird engine what to do. And thats all do-it-yourself.
A potential customer sees a refitted A27 with a modern fuel efficient outboard? IMO a 2015 25hp outboard looks better than a 30 year old Nissan Ld28. BTW in the life of the boat, five years from now, even if the new outboard dies--its still cheaper to buy a second outboard, than it was to repower, and then you're back to a brand new engine.
MY real reasons so far for not chosing the outboard yet are:
1) you cant heat your water or cabin
2) you can't charge your massive battery system
3) long distance you will save $$$ with diesel once you go past 5,000+ miles of use.
4) you cant go fast; if that important to you