I ski on the BigStix 7.6 ('03-'04 model) in 175cm. I'm 5'10" 160 lbs level 8. I like them a lot, but then I like the stable + energetic feel of Fischer skis.
I have only skied narrower Atomics (BetaRide 9.22) and I know that I don't like their feel of highly stable, less energetic compared to Fischer.
I haven't been on the 7.6 in powder or crud yet... only packed powder, ice and windpack. in harder snow conditions they are a smooth, energetic and powerful carver, but will tolerate some feathering of the edge.
I have the 8.6 in a 180cm and use that for deeper days.