Stroud:
Although all strait-stocked, there is a 3/4" difference in length of pull between the Sauer and the other two (guild gun and the Manufrance 16. The guild gun has a good deal of drop cf. to the others. I'd find the skeet-ic or ic-full most useful because I just like an open choke in there somewhere. The Froggie 16 would be pretty light for me and I wouldn't control it well but you might as you've got a 20 gauge o/u. You should ask about chamber length and cast if any if your experence tells you you need some to get your eye over the middle.
I doubt if you'll find Thaddeus overly chatty. Maybe that's a good thing because he won't charm you into buying something with the ribs falling off either. I didn't buy my first sxs sight-unseen because there was a local consignment rack with a few sitting on it but perhaps you don't have that option. As suggested by John Marin, if you can find an Uggie model 30 with light use for 4-500$, that might also be a good first choice and save half for the next/better one. My .02.
jack