+1 Brands are pretty meaningless.
I have mixed radial and cross ply when I wasn't willing to deal with trying to import stuff into foreign parts when I could just buy the "wrong" one (think it was a X-ply rear that did 3000 miles paired with a radial front on the F650). Honestly I don't see what all the fuss is about, but there again the nastier East European plod could just chuck you in the Gulag regardless and the Western ones can't read the codes while you are at 60 mph. I would have to be pretty stuck to mix them in the UK though, it would be my luck to get caught in some roadside VOSA thing.
Andy