@dc42 Update - Sorry its been a while have has car trouble...!
So the issue with the weird steps per degree was down to belt tension, that's resolved now.
This is my config file it's pretty simple.config.g
Unfortunately the Gcode file is 43meg so I cant upload it.
I've just generated code for the first 20mm of the part in S3D and here's just the base, the full test print is 1100mm tall. Its a spiral thin wall print.
The printer struggles on the brim radially from where the wall stiffeners are, and also on the main part wall when running above 125%. The printer will run faster but stutters quite a lot. The previous video link is still representative.
As an aside it also looks like the max deg/sec limit on the bed doesn't work when doing relative rotational moves, i.e. +120deg. Is this normal? I think the limit is working for normal operation.
Any thoughts would be much appreciated.