I use one but I dial the bass in mic input and use an equaliser pedal, till now no problems with it. I play indoor not outdoor so don't know if it is a good ideia.
As I said here
Roland Street Cube amp
and requoted here
PA system for busking
I used a Roland Cube Street, the non-EX version (so if you or anyone else are discussing the EX, be warned that I'm going partially off-topic), once.
What you do is what I also would have done (except I hadn't thought about going through the mic channel, which I couldn't because I was also singing lead) if I had an EQ pedal, in order to
cut bass and boost the signal at the same time. I didn't have one with me, so I had to select the less "farty" pre-setting the Cube has (again, *I* am talking about the 2.5+2.5 watt, non-EX version,
not the 50W Cube Street EX).
Unfortunately, that was the Marshall guitar valve amp emulation setting. So I was distorted as all hell! And yeah, the tonal result was just as horrible as you can imagine. But at least it was electronically-induced distorsion, not the speakers going into overexcursion and about to blow, and the volume was...well, the most I could squeeze out of the thing without extra equipment.
Speaking of which, the other significant difference with what you do with the outboard equaliser and what I did is that when using the amp outdoors and in front of an audience you'd better
cut rather than
add bass: the tone will be even less satisfactory,of course, but the amp section will be relieved of the task of producing lows, so you will be louder, and the speakers will be less stressed.