In reply to peter pan:
each to their own mate, aslong as they can't slip off!
my old shoes used to be a size to big but fit like normal shoes and they worked for me but it did affect my footwork
I have now got a pair of evolve pontases that are the same size as my shoe, they are tight but not so tight that they are painfull.
your footwork will be better with tighter shoes but it depends if you want to sacrifice your comfort. I know i cant climb properly when my feet are uncomfy, its finding the right balance for you.