Question for ARC aficionados

Thinking of "downsizing" my system. I currently have an ARC LS15 and a VT100 mkii. My question is: What would I be giving up sonically(other than 3 db of headroom) if I replaced my current ARC pair with a VSi60 ? My speakers are Acoustic Zen Adagio. My room is about 15x20x9. I do not listen at ear splitting levels.