In terms of technology etc, 50D should be much better. For AF, ID MKII is the winner though. Give and take, decide on what really fits your requirement.
shoot what? stationary object need fast focus? or fast moving subject with no clear contrast for focus lock? i find it at times miss focus due to not able to find a contrasting area for focus lock. also 85/1.2 is slower than 85/1.2II. but i still thinks 85/1.2 is still not that bad.