Giving a XP boost to DPS instead of tank.

[Ilenya]

Alternatively, how about allowing one's roulette experience to instead be given as rested exp, thereby applicable to any class?

That'd at least encourage many tanks who don't want to waste their roulette experience on something other than a DPS to tank and then spend the DPS experience with fewer dungeons for the same gains or via any more accessible form of leveling.

If you are going to do something like that, may be safer to create a new pool of rested exp to work with.