Hi Stefan!
The float position is rather nice to have, I found.
I solved this mechanically, which won't help you - but the experience of the float position has convinced me that it is worth some headaches to get right.
Have you thought about adding an extra valve for each cylinder's float?
Similar to this:
Blade lift float circuit for motor graders 4034815
http://www.google.com/patents?id=Aks...0valve&f=false
On Caterpillar's new M-series, the float is activated by the operator pressing the joysticks forward over an indent - not sure what Volvo does and also, with electrohydraulics, the joystick does not tell us anything about what happens on the valve side of things.
I see that you have laser-cut the gears for the circle - can you comment on how good the quality of the surface is - do you think it is good enough?
Cheers
Jens