3 Summoners with different loudouts are horribly effective. I like the prime myself, soften up with the lrm then you still have a lbx20 plus a CERPPC to really dish out the hurt.
Yeh its not minmax like the a, but when your playing as a team i find that the prime can exploit anything anywhere and really dish out the pain. I can kill anything that can catch me, and can outjump /outrun the majority of things that might give me trouble.
Ever since i first fired that slow assed ball of plasma ppc in mechwarrior 2 from one of these ive been a huge fan.