I'm working with footage from a 7D and a T2i on a windows machine. Since I don't have Premiere CS5 I still go the way of transcoding my footage to DNxHD with MPEGStreamclip for smoother editing (or to be honest: for being able to edit at all ;) ) and then color-correcting and grading in After Effects.
What do you think: When using DNxHD, is is better to stay in RGB (Canon VDSLR footage is RGB, isn't it?) or to convert during transcoding to 709, which is possible with MPEGStreamclip and DNxHD?
We convert to RGB and 10-bit color space (Quicktime) in MPEG Streamclip. Do any initial cleanup in AE of the files and fast import into Avid. Once done with the edit, we will CC in either Color or AE and reimport/relink (depending). This has been our most reliable workflow so far. Once conformed and completed we output in 709.
This is working for us without many issues. Hope that helps.