i just checked over my SLs, they freewheel fine and back pedal fine, my drive train makes a nice mechanical noise when pedalling or back pedalling. You can hear the ratchet clicking away when freewheeling and back pedalling too, but i don't see, hear or feel anything that could be construed as drag.
I felt something not too disimilar to worn bearings, i took the wheel off and checked everything over, but i cant see anything on the cranks, bb, mech or wheel that would suggest something is wrong, i think its actually just my chain engaging the chain rings lol.
I have heard crossmax freehubs can be a bit tempromental. You need to take the cassette off and service the freehub body (clean and oil) and see if that makes a difference. However, the 'purring' noise when you back pedal sounds to me like the pawls moving over rather than engaging(which is normal for back pedalling and freewheeling is it not?)
