Wild,
I have 2.5 acres and bought the TC34DA. In fact, since I am wanting to purchase more land in the future, I even considered the TC35/40 series (to the point of demo-ing one on my property). The 34 is not overkill.
I guess a lot depends on how close the trees and other obstacles are on your property, but I have found that my 72" RFM works fine on my property with this set-up. I don't even take off the loader - just drop the QA bucket.
I think the mid-mount mower would feel even more agile, but comes with the on-off pain of a mid-mount and you lose the non-universal benefit you have with the RFM.
As far as compaction and industrial tires are concerned, I have had no regrets there either. But this depends on a lot of factors. My yard is well established (grass and unfortunately-weeds rooted, dirt settled) and soil is fairly hard/rocky. The type of grass you have could also factor in - fescue in the south is pretty hardy. Also, I am not attempting to establish a "Southern Living" coverpage worthy lawn. Don't get me wrong - it looks very good after cutting, it just doesn't look like an exclusive golf course. Keep in mind that with either tractor and tire setup you are looking at - you will have enough power that if you lose traction you can tear up the grass.
See if your dealer will let you demo the 34, all you need is a couple of passes to figure out if it is too big. If it is too big, you will never question if you should have bought more and the lower price of the 26 will add to your buying experience....
Rich