After some fiddling I just managed to make a first dry run of the printer, looks very promising! It didn't seem to have any problems moving up to the firmware limit of 300mm/s, it could probably do 400 or more; very quiet too; I'm completely sold on linear rail bearings now.
I was a bit worried about the Z axis, but that also works pretty well, although the calibration is completely out of whack.

Now I have to do the heated bed installation and it's ready for trial runs.