Unfortunately I have the same problems with the Hiwin rails from Blurolls: The carriages don't run smoothly along the rails but have heavy hickups. I have recorded a video showing this effect: https://youtu.be/JxpSd8auNP4
As you can see, the carriage gets stuck halfway accros the rail (and also on some other spots that are out of shot).
I already disassembled, cleaned and relubricated everything with lithium grease according to Hiwins recommendation, but that did not help either :(
Currently I'm in the process of talking to the seller to try and resolve all issues.