I have had one on my CT but since removed it due to losing the space on the grip. The heated grip moulded shape around the wire and the vista clamp thingy combine to use up approx 25mm of the inner grip so after hardly using it in Scotland in May i removed it. I wished i had put it back on for the Alps trip last month though as my right arm could have done with some respite on some of the long fast stretches of motorway/autobahn.
I have used my vista on about the last 5 bikes when embarking on long journeys as i have ongoing problems with tendonitis and grip in my right arm and can then ride left handed for a while to rest it
There may be a bit of farkling required to fit one to your bikes though and remember that they only hold the throttle in a position, the speed is free to fluctuate as the terrain alters (eg. an uphill road would slow you down a little and vice versa)