If anything goes wrong with the conditioning cables, TAC is going to ask you to install equipment to the proper specs. I personally have run into the opposite issue recently where a user had 1 meter of singlemode cable with multimode gbics connecting a controller to a switch and there were alot of errors on the interface. After trying a bunch of combinations, we had to replace the gbics and the fiber (both to multimode) to stop the errors and stop hundreds of access points from rebootstrapping.
If you have time, you can experiment. If you do not, just do it right the first time.
EDIT: There was also a switch between the controller and the real layer3 switch that was a cut-through switch, so none of the errors showed up on that switch, which made figuring out what was wrong even more time-consuming.
It would be interesting to hear what others have done.