If your running a 'special' rear wheel it doesnt matter, as per the SPIN on my old Tempest mated with a HOPE front hub on Mavic 221 rim.
As for normal wheels, I think as long as the rim colour matches then no problem. On my Karakoram I'm running a Pro-Circuit front hub on Mavic 231 rim and a Sunrace rear hub on Araya rim.
My Stumpjumper and RTS wheelsets both match.

As for normal wheels, I think as long as the rim colour matches then no problem. On my Karakoram I'm running a Pro-Circuit front hub on Mavic 231 rim and a Sunrace rear hub on Araya rim.

My Stumpjumper and RTS wheelsets both match.