I do not have a Sig large frame, but I have several large frame AR’s. I have a KAC SR-25 ACC, a GAP-10 6.5CM, and an Aero Precision that’s being converted into a 18” 6.5CM. If I was in your shoes, and didn’t know for 100% sure that I was going to love it, or go all in, I would look heavily at the Aero. You can find them VERY affordable, super easy to work on, and every one I’ve ever messed with has been great quality. They are made of the right materials, 416 stainless 1/8 barrels, and they’re $1500 brand new.
Dig HAS NOT been impressing me with their rifles. I’ve personally seen bad carrier tilt with their piston guns, and heard stories of bad CS.
IMO, of course, KAC is the pinnacle, but if you don’t have the $$, that’s very understandable. Not many folks do. The Aero gets you in with a decent gun that you can upgrade/adjust as you go.