I have no noticeable difference from the standard Saint levers, Leon. I have my levers pull quite far back into the bars (to try and reduce the arm pump) and quite a fair bit of travel compared to some. It feels pretty spot on to me. Certainly as powerful as the saints were.
I've a saint caliper up front, and a zee caliper on the rear and no problems at all with either. The Zee caliper has the two bolt configuration (compared to the four of the M810 saint caliper), and hasn't had any problems at all so far, touch wood.
With regards the stem / bar height, I measured for 'Dman' the other day and the centre of the bar sits at 105cm. I do sometimes consider another stacker, but it seems to be working at the moment. Its all about being comfortable on the bike at the end of the day, so depends whether your back can handle the lower set-up.