I play faster typically with rounds, however I have recorded death metal with a p with flats and fingers, so assuming I warm up and stretch properly I dont really worry about that. I DO play and prefer mainly flats because I can go anywhere on the neck without finger noise, from way up high to way down low all muting with my fretting hand. I like flats more, the note to me feels more defined/whole, easy to point out where it is in a mix, and easy to record. I do keep a bass strung up with zingy rotosound rounds though, because even though sometimes I prefer flats it's best to swallow my pride and do what's best for the mix.
= didn't like the feel.