I shoot at 1600 and develop normally. Portra 400 has phenomenal latitude. You can also push process and that works as well. Pretty forgiving stuff.
I have read that it will go to 3200 but I have not tried to do it myself. Hmm..I may have to try that out during my next color developing run.
Edit - Keep in mind that I scan my color work. Not sure what will happen if you print in color in the darkroom.