Maybe the Commandos had bigger better balls or something, but my Notrun Atlas and 650 Dommie engines wet-sump summat awful, with known-good guts. For better or worse they've got taps with mag cut outs. Same as my AMC twins, which are notoriously evil on this. Uprated and modded pumps can help at a price, but not guaranteed in my experience with the AMCs . Maybe the Norvil etc replacement pumps do a better job for Notruns like SRM ones are said to do for us here.
My A, though, hasn't misbehaved at all since replacing the ball and spring. Before, it was very unpredictable.
When bikes were daily transport they didn't have a chance to embarrass themselves, though, so we never really knew I don't think! Whether, for example, later A50s and A65s were better or worse, I don't know, because the ones I knew back in the day were all daily riders. I very rarely see the unit twins hereabouts. Folk prefer the pre-units (there be loads of 'em), or maybe the unit ones just weren't imported here in any numbers.