the 68mm 10 blade has a more aggressive blade curvation, if you plan on running nitrous, use the 71mm 10 blade wheel, and stay away from the 68 wheel. the 68 wheel will have more back pressure than the 71 wheel. both are good wheels, but they both should be used in diferent applications. as far as benifit, i would use the 68 wheel is your are looking for a fuel only quick spooling street, or sled puller. it is going to be slightly slower than say the 65 11 blade wheel, but the flow is hands down better with the 68 10 blade, and even more with the 71mm 10 blade.
Wes