Just ordered mine five days ago. Due to the Chinese new year it should arrive at the end of the month in Italy, and then probably one more week till Romania.
Did allot of reading on the internet, and also saw some interesting youtube video with owners who already use one, stating the pros and cons of the mount.
In the end, if I would manage to guide it as my avalon m-zero, I would be really happy. There is a common opinion as the RST-135 guides really well with short exposures 0.5-1s and small and aggressive corrections. We'll see how that goes.
On the AZ adjustment, if you load gear up to 8Kg, I guess it shouldn't be a problem while aligning, and if you go over that, just simply use a counterweight.. or maybe I'm mistaking..
Would be really interested if some of the existing users would post some guide graphs here, together with the RA/DEC/total RMS they got.