I've got a heavily modified kossel variant, with a smoothieboard controller:
Volumetric extrusion support would be very nice -- It allows me to not worry about what filament I sliced the model for -- I just run M200Dx.xx for what diameter the filament I have loaded. it works very well.
Both Cura and Slic3r support this, and should be trivial to support -- under the hood, it would just set the filament volume to 1.128379mm, far as I understand.
http://reprap.org/wiki/Triffid_Hunter's ... ic_E_units