From my short time with a 10900F, I can say that you can definitely override the power limits, but as far as I can tell you can't override the boost frequency limits (whether directly, using MCE or any other method).
I briefly had a 10900F drawing 500w of power in Prime 95 small FFTs. That was way beyond the standard power limit for the processor and I maintained it long enough that the short term boost should have expired. It ended up being throttled by the motherboard VRM overheating, not the standard power limits. Obviously due to the absolutely insane power draw, and the fact the VRM was bordering on overheating, I didn't maintain that for more than a few minutes.
Unfortunately, in things like gaming, the load on the CPU isn't actually that extreme and you're not that heavily power limited. In that situation overriding the power limits by itself while not being able to adjust the boost frequency just doesn't help you that much.
Personally I would not recommend any of the non-K parts unless you absolutely don't intend to overclock, and by overclock I include even using MCE (sets all core boost equal to single core boost).