Canon says the 50D will do 90 shots at a burst rate of "up to" 6.3 using the UDMA cards, and 60 with non-UDMA cards.
Canon doesn't say whether the burst rate is affected by UDMA cards. My guess is that it would be, but I'm not sure.
Here's where Canon talks about this:
http://web.canon.jp …ng/eosd/eos50d/02.html#01![]()
pmk

