I used to think the E1 would be much better with the zooms, but my mind's been changed. However, the new tele-zoom might really be EVF only, in which case the Pro1 holds no edge if that's lens you will use a lot.
Otherwise, it's all about handling. Do you want/love/need/hate the OVF, and how does the size of each feel? Those are the questions.
There used to be a bigger price-factor, but there are some very attractive deals on the Pro1 these days.
Both fine cameras.