I concur with the opinion that there is nothing wrong with 2-1/2 inch chambered guns. While I favour 16 over 12, the reality is a 2-1/2 in 12 gauge is a fine gun and likely the best value for the dollar. I further concur with the opinion that auctions are often either junk being dumped or high value items going at a premium.
A 12 ga 2-1/2 gun will weigh the same or less than the standard American 20 anyway
I do not concur with the view that sleeved guns should be passed on. A quality sleeving job is just that and while it may not be the same in terms of value as pristine original, it is less likely to cause issues.
If this is to be your final gun then hold for the perfect one, if not then consider a sleeved one as a way of getting more gun and features than otherwise can be had
I have had the adventure of buying what I thought I wanted only to discover it was not. The love of doubleguns is more like a pilgrimage in which the journey is as or more important than the objective.