Yeh I've noticed that with a few DJs. Jon O'Bir's sets at Gods back in '04/'05 were the best I've seen him play, whenever I've seen him elsewhere he's not been up to the same standard, perhaps it's a comfort zone thing?
Jules @ Gods is another one I've noticed, I've seen him there plenty of times but only once has he really been on top form, back in Feb 2004 when he played after Ferry, that night he was immense.