*shrug* my foot wear varies a little, but the two sets of shoes I drive with are New Balances which can be a bit clunky to try and wrassle MGB peddles with, and some thin slick rubber soled "deck shoes" which have quickly become my favorite driving shoes. My rubber brake peddle pad came off some time ago. So, I've been driving around with the bare metal peddle for about a month now. I had some problems while the pad was still hanging on for dear life, but since it came off, I haven't had any problems with foot slippage on the bare metal.
Then again, it doesn't rain much out here. So your miles may vary.