I'm not sure what I have to offer on this subject will be useful to you as I have almost no hands on time with any chain mortiser (exactly one mortise with a Mafel at Heartwood School).
I did stop and take a look at the Protool this past weekend at the eastern conference. Fit and finish looked good, the design is similiar to the Mafel. I didn't spend much time or ask about setup and operation so I can't comment on ease of use etc.

Perhaps a Google search will lead you to a review... If you do decide to go Protool I'm sure that a number of people who follow this board would appreciate hearing from you on how it works out.