With the competition in the 5.56 assault rifle arena, combined with the down economy, right now is a great time to buy a Sig556. I bought one early on, but not early enough to score the Swiss-made parts (only assembled in USA). Therefore, mine is one of the "bad" ones that were early US-made parts. I must admit, I had some functioning issues with cheap ammo, but using M-193 or M-855 quality ammo, it's 100% reliable. I bought a real peep sight that mounts to the rail, and my buddy refinished his and mine in the "Sig Grey" cerakote, and I think it looks as good as it shoots now:
My buddy was doing the refinish, because he decided he wanted a real Sig550-like rear sight set up. He bought a de-wat Sig receiver chunk with the original sight, cut if off, cut off his gun's picatinny rail so it butts up against the sight now, and welded the 550 sight onto his receiver and refinished both our guns. Here's his:
As far as the qualities of the weapon, I think you already have a good handle on the differences. I'd add that the trigger is amazing, and the accuracy is top-notch for a battle rifle. It may not beat Noveske's but that's apples and oranges, I think, because the Noveske's are custom and much more expensive. Put that kind of money into a Sig 556, and it would shoot right with the Noveske's I'm sure. (Really the only thing to do would be free-float a heavy barrel, which would probably cost less than a Noveske.)
With the iron sights on mine and M193 ammo, I was getting 4-5" groups at 200 yards, which is better than I thought I could shoot with these spectacles...
As far as a field-gun, it is a little heavy, but so was the Garand... I got a Giles Tactical Sling, and really like it as a carrying system.