Motorola SF600 works fine for talking, playback!
Jolla sets volume to 50% by default when you press play and asks for confirmation. also, the volume is set separately on device and headset, i.e. when you set the device to max., that isn't the highest possible volume unless you also set the headset to max.
When I had Jolla on 50%, some of the classical music was barely audible, I actually needed 100% on Jolla to get decent volume.
EDIT: when swithcing bt on first on the Jolla, then on the headset, it does make the connection automatically, but the sound is weird, metallic and distant. To get proper sound, it's necessary to switch the headset on first, then turn on bt on the Jolla and initiate the connection. that is the other way round from what I'm used to, and I find it pretty cumbersome, bcs you actually have to go into the bt submenu of Settings app - they gotta find a better way to do this.