I have the SMH-10R and the speakers sound fantastic!
Well, they sound fantastic if you can get them cupped over your ears like headphones, but you can't with the way their made.
The only way it would be possible to get decent sound out of any of these speakers would be to take the ear pads off some headphones and build them into your helmet.
The Sena have spacers available to get the speakers closer to your ears. I tried them but they only mashed the hard speakers against my antihelix.
I haven't worried about it since I got the B, I prefer the cluttered, imperfect sound from the stereo mixed with all the sounds of riding to the isolated experience it would be to have helmet speakers that had a good enough seal to have substantial bass response.
The Sena is great for answering phone calls that I never get and I occasionally go for rides with an ST1300 buddy who has a different BT system that the Sena can connect to. Scala, I think. The lack of bass is not a problem for human voice clarity.