I ride with my brakes the 'wrong' way round, no particular reason other than i want to be different, it wasn't overly hard to get used to it, took about a week or so maybe ? Once your used to it it's no biggie, although it's crucial to warns friends before hand, especially with  mega sharp brakes   It's a bit of a pain if your buying disc brakes with reservoirs, means you have to switch the levers round apposed to running them upside down, i'm lazy so can't be bothered with the hassle