My 2 cents, for what it's worth.
I have a Camper 2x12 which is said to be 2 x 180 watt power section. (I know this is a different beast to the CX).
There are two inputs, left and right/both. I use the "both" from my monitor out controlling volume from the KPA master. I use this for stage monitor, FOH goes direct and is not linked to the master volume. I don't miss/want for a volume control on the unit itself.
I agree with a previous poster in surprise the CX could not keep up with a loud drummer. I cannot have my output to the Camper above -14db, and usually have it lower. At -17db I have long overtaken the other guitarist using Marshall half-stack, and the drummer needs side fill to have a clue what he is hitting. That is not because he is afraid to hit his kit, he is as loud as any I have heard.
I guess what I am saying, at least in the Camper 2x12, there is huge power reserve. I cannot imagine a scenario when I would be left wanting for volume. I suspect the test unit has a flaw, unless the company has employed a completely different power section.
I have not compared the Camper to the other units tested in this thread. I am in Australia and don't know the Matrix is even here. The CLR is a two hour drive for me to try, and I haven't felt the need (even though the Camper is not a FRFR and is a little dark sounding. I simply adjusted the eq in the monitor out to compensate and it works for me).
Regards to all.