My K0 has an adjustable "throttle friction lock" that helps offset the pull from a strong throttle spring. Having that properly set up made a huge difference.
That said, I use one of those "vista cruise" throttle locks, the plastic thumb-lever ones. I can lock it and let go with my right hand, no problem, but even when locked I can twist the grip to wherever I need it.
I don't think I'd like one of those throttle bosses, but I suppose it comes down to personal preference.
mystic_1