Definitely still playing slow. I'm not sure where the idea of slow being broken came from, or how it was tested. Even on default it seems fine. The main thing I've found, both now and the beta, is that the accelerate feature they added does put a disadvantage on the defender, but with the right combo that doesn't matter as much.
From a controller perspective, I've learned to "pump" the sprint button when I need to get up to speed faster. Also though, the sprint speed lowered evens out the playing field regardless. Overall, no issues at all with slow for me. Anyone can play normal though - they just haven't been tested as thoroughly with them.