I don't think it would hurt head to head play at all.
Also, I checked out the gamespeed at 50 with player edits for Detroit and Denver and it played pretty good. The only thing I noticed was players that didn't have very good stamina moved slower than others as the game progressed. But to answer your question I think it does work better on 50 still because like you said it helps to see the teams run the plays better especially from Baseline camera.