As an example of used. If you want a 12 gauge, right now The Gun Dealer in New Brunswick has an Ithaca 200E (ejector) in 12 gauge listed as very good condition at $599.00. In my opinion, the two guns you mentioned don't even compare to this gun. And if you end up not liking SxS's, the Ithaca will bring more than the others at resale.
Or there is a FEG 12 gauge listed on the EE right now for $395.00. I have a very nice FEG and I can tell you they are a well built gun plus true chopper lump barrels. But if you want to get ino SxS's and want new but only want to spend around $500.00-$600.00, then you are limiting yourself pretty much to the two choices you mentioned. Of those two, I also would pick the Baikal or maybe Yildiz.
But as far as used, there is nothing wrong with buying used SxS's if you know what to look for. Of mine, only one I bought new. In fact, for me, the older the better.