Some do tighten the diff to that extent (or make it barely turnable, just enough to get some "diff action" and make it TCS legal.. ), and I think it does pretty well.. the initial turn-in does suffer a bit since the inner wheel won't turn slower than the outer, but acceleration out of the turn is what makes it great, as no amount of wheel-lift will rob you of power.

I think it takes a little adjustment in driving style to get your steering back, but it can't hurt to try..