The bus design appears to be the same. However, I think the problem with the bus stems from the popularity of the half-size (0.5" sp/1" dp) breakers that are/were available for these panels. In my eyes the problem is that a lot of the half-size breakers wiggle a lot even with the cover on. I think the “stab” part of the breaker connection on the half-inch breakers is pretty poor. I think it gets even worse when you have high amperage 240V circuits using the 1" double pole breakers. In fact it is possible to install those breakers to the same phase because of how the bus is designed…kinda funny. I will note, however, that the bus stab mechanism for the full size breakers (1" single pole/2" double pole) is SIGNIFICANTLY better.
Aside from a recall of some 1996 FPE breakers, the FPE stuff isn’t exactly generating much press up here.
My favorite breaker panel design of all time is the Sylvania/GTE panels. The breakers actually screw into the busbar. No concern of them ever falling out when taking the cover off, and as long as the screws are tight, the connection is good. Those were very popular here in homes built in the late 70s-early 80s. These were also branded up here as “Commander” and a few others.