Jack,
I'm not very clued up on the Shetland versions, but yes, if it is a cream hull then it will probably be a Shetland. Not sure exactly when Arnie Holt bought the moulds from Shetland but I think it was the mid to late 90's.
The reason I bought an Alaska instead of something like the Warrior was that the Alaska is rated to carry 6-8 persons versus 4 on a Warrior. I wouldn't want to have 8 people in an Alaska but she's easily managed 3 adults and 3 kids. I regularly fish with 3 adults onboard with no problems.
In terms of handling, the Alaska has got a wide beam and so rolls less at anchor or when a person moves about when steaming. I like that!! On the down side, the wider bow can cause a little broaching in some seas (but rare) and can make it a slightly wetter ride at times, but that's usually a good signal to tell you you should be going a little slower in the conditions.
What would I change on the boat? I prefer the new Alaska layout which has single swivel seats on both sides, and I'd like a folding canopy instead of the standard fixed version, although I have now found a way of folding it away.
Not sure what bouncy was in the Shetland hull, but the Arnie Holt versions have terrific bouncy installed. Arnie showed me some impressive photos of the swamp test they did on the Alaska as part of the CE certification. The boat was diliberately flooded but was still floating with 4 or 5 people jumping up and down on the hull.
Yes, weak floors were a problem on some of the Shetland versions and also heard about stress fractures around the transom area. Look for stress fractures in general, especially if it has been trailered on an old trailer which doesn't offer the support of the modern roller trailers.
And if you buy a boat with an engine, check that it has a serial number. I know this is an obvious thing but it's easy to forget. If it doesn't have a s/n leave well alone. Even engineers forget to do this.
You'll enjoy the Alaska, which ever version you get.
BF