Scott...
The SRM350 has only a very slight decrease in volume output compared with the SxA100. So slight it really shouldn't be refered to as a 'downside'. On the other hand, the increased fidelity is also by a small amount, that is, subjectively speaking IMO.
Therefor, the 350 will work well where ever the SxA100's works, for most small and medium sized venues.
As I said, the SRM350 is an excellent speaker... but then, so is the SxA100. With all it's pre-release hype, I might have been expecting more. I'd give the new Mackie only a slight edge over the Sxa100. It's smaller size and weight (32 lbs vs 43 lbs) may appeal to some.