Personally, I think PIATs are a bit OP with that whole hitting tanks from invisibility. But then, at least that is the way you are meant to use them, not blobbing them like an a**hole.
Also it should be noted that they can only cloak in cover, PIATs aren't that difficult to use. Sure are they as good as shreks - noe, but what is?
Bazookas. 90mu for two, 180 for four, on a very resilient platform. Same deal with RRs, which are more accurate at long range.
Honestly, the schreck is really not that amazing.