Looks like a fine boat, as for the brand, you won't find anybody on this site that does not believe that an AM skier is as good or better than the top ski boats in the world. Quite frankly because it is.
Don't kid yourself about the floor being an easy fix. I thought the same thing about my 85 Advance this past fall. I had a soft spot in the same location and thought the same thing, patch it, replace the carpet, and I'm good to go.
Under that floor is floatation Foam, and on a 23 year old boat you can bet it is water logged. A common problem with ALL ski boats is this, over the years it Collects condensation and becomes vey heavy. You would be doing yourself a huge injustice by just patching that spot.
However, if you are handy, with the support of members on this site, this is a project you can do yourself, for 1000.00 or less. That being said, I would still consider this a good purchase. Even if you have to put 3500.00 into it you would have like new boat for 10,000, and with the price of new boats today, you can't go wrong with that.
Good luck, Keith