It doesn't really matter so much who plays the drums. I was very surprised to find out that Ashmedi writes about 98% of the drum patterns. That way, everything works to help build the actual song, instead of all the musicians showing off what they are capable of.
I do miss Proscriptor as well, though. There was something about his playing that was really unique. His playing is very charismatic and natural. Xul is an amazing drummer as well, but he kind of lacked that certain quality that is unique to Proscriptor.