I am playing freerolls at ACR. I find software to be buggy. I am on Mac by the way. Connection issues, registration issues, randomly make me sit out . Definitely not a good experience. Is ACR software better on Windows?
There is quite a bit of weird stuff that happens on ACR, but it usually comes in huge waves related to DDOS attacks. It is generally quite stable for PC.
I love Sit 'n Go's, but it's hard to find a 27 runner tourney that doesn't have an odd twist. On ACR/BCP (WPN network) they only have "On Demand" tourneys in this category, and for me, a SnG shouldn't have late reg, and I don't like "turbo".
BetOnline and SportsBetting (Chico network) had a promo last Xmas that required you to play in cash and SnG's (it varied day to day) in order to win entries to fairly big FreeRoll's (around $500-1000, IIRC). I would explore this option if I were looking for US friendly SnG's. During the promo, you might get an inaccurate sense of the usual playing field in terms of number and quality of players, but at least you can check out the software. And the software is very smooth, except that it kills the sound on any poker site that I have running at the same time. There are horror stories about withdrawal from BOL and SB, but they usually are FR winnings issues.