PIAT is more late game AT than anti light vehicle rush, I prefer Tank Hunter Section or AEC + 6-pounder. Also people keeps forget about mines: always lay mines when you have surplus muni, especially for Soviet and UK who don't normally get good AT, a light vehicle run into a mines is usually a death sentence for it.
It is. PIAT can do it though if you can micro it well enough. Attacking super heavies with PIAT is easy, they are really slow. Damaging luchs takes some serious path predictions so it is not advised for players who can't spare their apm.