i used to run 42a's on both and i recently just changed to a pair of 60's
the grip is still preety good but i wont be buying this grade again, its obviously not as grippy as 42's.
they doo last a long time though, by now on 42's (3weeks) my tyres would be showing reall signs of wear, not on 60's though they are hardcore.
if u get em cheap go for 42's, if u pay full 25 smackeroonies then probably best to go for 60's, unless u r wadded.