Alaska - Whitewater rafting

My brother and I will be visiting Anchorage at the beginning of July and would like to do some Class IV-V whitewater rafting. It looks like the Six Mile Creek/River is our best bet. I've identified two outfitters that run this trip: Nova (http://www.novalaska.com/day-s.htm) and Chugach Adventure Guides (http://www.chugachoutdoorcenter.com/six_mile_rafting.htm). Any advice or recommendations as to which outfitter to use?

Nova has a great reputation though the other company may be just fine too. Hopefully someone else will chime in with some thoughts.

To answer my own question (in case it helps someone else), it sounds like Nova is the only outfitter running Six Mile. Chugach Adventure Guides is just a booking agent for Nova. You can also book directly with Nova.