Worth upgrading from a 9920 to a Quark 125?

[Rtsbasic]

Using a 6v UBEC, which works fine - no stuttering on servo's. It only stutters going to WOT immediately, if I ease it in over the space of a second or so its fine. Its also fine pulling away to a medium speed, although it does cog for that split sec.

Caps aren't leaking, although there are only two on my model. 650uF 50v ones I think, not 100% though. One is easier to move around than the other, perhaps its become disconnected.

Btw do you know if the 9920 has thermal cut off? I've never encountered it so I presume it doesn't?