I have owned both, and both drive me nuts for different reasons. I love the 3800 for everything except its very poor paper handling. Related to paper handling, I often get black splotches at the end of the paper, as there is no vacuum system to hold the paper down flat. A real bummer when you are feeding expensive cotton fiber papers through one at a time.
I do miss the better built 4x00 series of printers, but I switch back and forth between MK and PK quite often. It is likely that I will be moving to an IPF5100 soon, though.