I’ve been pushing black & white film (specifically Tri-X 400) with great success for a while now. I usually shoot Tri-X at 1600 and then stand develop it in either Rodinal 1:100 for an hour, or HC110 1:100 for 1.5hrs. I’ve also tried actually push processing it in HC110 (dilution B and H) for the required amount of time, but I’ve just found stand developing to be easier and produce very similar results.
So then I decided to try pushing C41. Since stand developing is not nearly as common for C41 as it is for black and white developers, I push processed it as well. I started with one of the cheapest current production color films on the market, Kodak Gold 400 (sold in the US as “Ultramax”), and pushed it 2 stops to 1600 just like I do Tri-X. Then I processed it in Unicolor C41 at 100F for 5 minutes instead of the usual 3:30. The results are absolutely fantastic and I see no reason not to shoot Gold at 1600 on a regular basis.