There's a writeup over at SigForum by a member who got to handle one at Shot Show. The review was pretty critical and I suggest you check it out before making the impulse buy. I'm not sure what they are going to go for, but have you seen the Barrett M468? Seems like an incredible rifle - I would shop around before picking up a 556.
For the record, I am a HUGE Sig fan, but I'm a bigger fan of my $$$.
For the record, I am a HUGE Sig fan, but I'm a bigger fan of my $$$.