Unless you are going for a bright sound with lots of overtones, you can absolutely make it work.
I've not played rounds in more than 6 years, and I did gig in the rock and metal context. On my P bass, I have either Chromes or Fender Flats (the .105 set for tuning to D standard), but I've also used LaBellas in the past and have them on another bass. I do think they have a little bit of a lower thump than other flats and therefore offset the mids action of a P bass in a nice and musical way. Making it work is up to you, but as already suggested, a little drive from a pedal that can boost treble is a great help.
I've not played rounds in more than 6 years, and I did gig in the rock and metal context. On my P bass, I have either Chromes or Fender Flats (the .105 set for tuning to D standard), but I've also used LaBellas in the past and have them on another bass. I do think they have a little bit of a lower thump than other flats and therefore offset the mids action of a P bass in a nice and musical way. Making it work is up to you, but as already suggested, a little drive from a pedal that can boost treble is a great help.
