I don't think it is a useless external factor. I think it has a bit to do with the magic in the wet.
Oh, agreed that tread pattern itself isn't a useless external factor, but "looks totally awesome" probably shouldn't be a major consideration
Best lap time / AutoX shootouts and spreadsheet racing seem to put them at a dead heat.
I have no personal experience with RS3s on this car, but I have ridden in my friend's S2000 with them for a couple laps and a lot of daily driving beer runs. They feel really planted up to the limit and I think they are stiffer than the R1Rs. His turn-in feels crisper, but it could just be his driving. RS3s aren't terrifying in the rain, so they're at least a bit better than R888s and friends for all-around use.
People with piggish cars like Evos and Porsches distribute a lot of anti-R1R hate at events I've been to. I think the R1R overheats and greases up more easily than the RS-3, but it doesn't seem to be an issue on our cars.
RS3 does seem to take a bit to warm up even on the S2K. They also seem to last a lot longer in street driving, so... :shrug: .
I think for the street I'd buy RS-3s and try them out, if just for the economy.