My observation is almost anything with TMCC or Legacy electronics run poorly on conventional AC, but it's not a fault of the drives. The inherent delays in deciding whether a command signal is there affects the overall running.
I've noticed that even with so called "dual mode" DCC decoders, a loco dosen't run as well on straight DC as it does without a decoder.
Even with a basic early TMCC rig, the new Flyer runs pretty well.
Rusty