The volume "lag" isn't that at all! I've had an M10 for 2 years as of this very day and love it.
What took a little time to adjust to is that the volume control is not like others. Though they say it's "linear", I refer to it as being "logarithmic." As you go up, it get louder faster. Get near the top and it will blow my eardrums out.
I use mine controlling it with either the desktop BluOS app or the mobile app on my tablet or phone. I love it, and the sound quality is incredible. I have had ZERO problems or issues with it. OK, there was one update they did with the firmware that put the display into a "light" mode that I hated. The complaints poured in and the issued another update to fix it within days.
Been fine since.