First you'd have to get a right side aspherical mirror to do a proper comparison. Considering the cost ($300+) and the leadtime (6-8 weeks) to get one it's probably not worth the trouble. I'm certain an aspherical passenger side mirror mirror would provide an increase in the field of view over the convex mirror.

Second you shouldn't need a wider field of view than the convex mirror provides unless you are one of those who dawdles along in the passing lane until you get within 100 yards of your exit. Then again it may help on those multi lane freeways, which I try to avoid.