The problem is the 57 trim isn't much bigger than a 50 trim, and it doesn't seem to do quite as well. Actually, it looks like it flows a couple pounds less than the 50 trim. Same for the 54. The 60 trim does like 52 lbs/min or something. It's easy to see why the 50 trim is so popular in light of this...
I like to follow Forced Performance's lead in this. They offered the Green (50 trim) and Red (60-1) and didn't bother with any of the wheels in between (54, 57, and 60 trim).
I would agree with them on this one.
680s will work with an AFC, but there isnt much room for tuning. The injector compensation will be ~33%, minus another 10-14% to get somewhere near 10.5-11:1, leaving only another 3-7% of range on the AFC. This becomes a serious problem on race gas when you tend to lean out another 10%
But it will "work."