I play in a segment of gigs where this thing comes in handy. We don't have amps on stage anymore, and we all play some sort of modeller or profiler. In the best of circumstances, we play our own IEM, but when we're in a line-up, we sometimes lack the change-over time to set this up.
Then, it can be something of a mixed bag: either the FOH/monitor-mixer knows what he's doing, or we all get a crappy mix. In the latter case, I have found that it is often times advisable to let the mixing guy focus on the lead singer, turn the other wedges you got from the venue off and plug your modeller directly into this Headrush instead.
It is loud enough for most applications, and you get a pristine, unaltered sound that you don't normally get out of a stage-wedge (or even your IEMs). It is mostly plastic in terms of build but not too flimsy, with correct specs in terms of controls: two separate 1/4" or XLR channels, bluetooth, a main control and mix through.
When I go out gigging, I always keep it in my car as a fail-safe. It is small and not too heavy, but it packs a mean punch. For bass, I would have probably considered the 12" version, but given the obtainable sound levels from the 8", in combination with the handy size and light weight, the Headrush people did a great job on this thing.