A little complexity but if introduced like the normal voting slider after a user has earned x amount in Curation Returns, it shouldn't be too much hassle or take very long to get the hang of it.
Perhaps before one gets the slider, their CR is the same as now (or lower) to deter abuse from alt accounts.
Edit: It could also be tied to REP so that way they also need to maintain a high enough rep to get full Curation.
It may be middle ground to lower the barriers for some on the fence to try different.