Ive had a decent run out my Cobra Chrome rear...it has slid a couple of times in heavy heavy rain but so would any tire i guess...diesel on the road etc.....I am going to replace it with the Exedra max for two reasons...First, they are 170 bucks cheaper than the chrome and second, i have had real good mileage out of the previous two exedra max's on my previous Rocket....They are 55 profile compared to the chrome at 50 so the stance will alter a bit.
Re the tire pressures, i think it depends on your riding weight as to the best pressures to smooth the ride out.
I go maybe 115kg with my gear...i was heavier but have cut the sugar intake!!...i run 42 rear and 38 front...works good for me.
FWIW..here in NZ a Chrome rear...240/50 16 is about 500 bucks nz...the Exedra 55 is 329 bucks nz.