I've had a good play with this now and I'm liking it.
Firstly I'm not a tone aficionado when it comes to practicing, as long as I can hear what I need to I'm good to go. But this little thing sounds good. All the sims are plenty good enough and the freedom it brings outweighs any downsides.
I haven't found it too bass heavy either, just set the bluetooth input eq to acoustic and it's quite bright, try other settings and see what gives you the sound you're after.
I don't know think the lack of a volume control is really a problem either, I've just set it to be a comfortable level and then just adjust my phones volume to match, if playing along to stuff.
One problem(?) I've found is that the manual says to hold the big round button for two seconds to switch to bass mode, it doesn't do this. I'm guessing the firmware has changed and this isn't a feature any more, or it is now and I need to update.
But overall it's great. Great to be able to just have bass, NUX and headphones. I've even found a short cable for my headphones so there's not even excess cable in the way.