They're using a two-stage trigger but I'm not aware of any aftermarket options yet. TriggerTech would be the obvious choice, and maybe SIG outsources the trigger to them already ... who knows.
I would buy a Cross if the safety locked the bolt handle, but since it doesn't it's not on my wish list. Too bad really since there's much to like about it. Who doesn't want a lightweight, short, modular, user adjustable, easy barrel swap, accurate rifle?
I prefer a 3 position safety with a position that locks the bolt, and my other hunting rifles have that, but I liked enough about the Cross to make an exception. It's a small thing, but I was really impressed with how the bolt goes together. No tools to disassemble, everything obviously goes together only one way, most of it is QPQ, just a nicely engineered piece, and the rest of the rifle seems is similarly well thought out (with the now obvious exception of whatever failure mechanism allowed the problem rifle to malfunction so dramatically). I also really like the easy adjustability of the stock, it can be set up to fit different individuals like a bespoke stock without the weight of most other chassis, or cost of an actual bespoke stock.
Also, LaRue MBT-2s kind of got me stuck on two stage triggers in ARs, but I have to say, I really like the two stage in this Sig. I have it set to break at ~2.5lbs, very crisp and nice IMO.
I wound up swapping barrels with a guy on The Hide who had a 6.5 and wanted a .308. Super easy to pull the barrel, and they use a neat double barrel nut system, one to headspace the barrel extension and another AR wrench compatible nut to attach the barrel assembly to the receiver. I'm not sure what the barrel thread is, but I was kind of wondering if I might be able to buy Savage or Remage Pre-fits and swap the extension at will.
I banged my rifle around a bit, slammed the bolt, partially lifted the bolt, etc and couldn't make it mess up. I guess I'll see what Sig says once they complete their failure analysis, but I don't see any reason to stop shooting mine in the time being.