Notsinatin: Thanks for the offer of testing that for me; it sounds like it is dependent on the hardware so I'd be interested to know if it works with the Sena. Tho I think they're quite expensive, if it works I'll have to suck that cost up!
But don't go to too much trouble.
Tomor: Thanks for the info. I have a Garmin 590 which I think it pretty good but I guess it'll depend on the headset.
rgds