Smoothieware rocks.
Much better results after switching from Marlin to Smoothiware.
Well worth the upgrade, thanks to everyone responsible.
It looks really good 
What did you upgrade from?
How is it better?
The improvements are to both the speed and quality of objects made.
Until recently my printer used a megatronics controller card, this is an arduino / ramps like all in one board running Marlin software. Its processor is underpowered to run the delta calculations at the speed the printer is capable of.
Problems in the finish including little bumps which may have been caused by the carriage slowing briefly. This problem has now vanished with the new controller.
I could never get the inductive probe to give consistant results before, this was partly caused by the slightly warped 2mm aluminium bed, this has been replaced by a 6mm bed together with a 500w / 230v heater which warms up faster than the extruder instead of having to wait ages for it to reach temperature.
Hth David.