I don't think there are many differences between the way that limewire downloads and bearshare does. For people with high-speed internet, both programs are almost always bottlenecking with the other person's upload speed, and not your download speed. If you think that your download bandwidth is being limited by limewire, here's a few suggestions:

-In tools->options->speed set your speed to T1 or T3, I believe that limewire assumes a set DSL speed.
-In tools->options->uploads try limiting the amout of uploads you allow. People might be downloading off you and using up all your bandwidth that way

If you are still finding that bearshare is faster, than i would use it. For me, limewire averages about 5kps faster than bearshare, but i think its just coecidence. I use limewire because I like the interface better, but its your call, they're both free so use whichever one you want.