I had an Ultra Classic. Took me a couple of days to get it right. It was fine thereafter.
Of course, my Harley was bone stock. If you have aftermarket pipes, or a low windshield, the additional noise will always want to break VOX when riding.
I left my Harley bone stock for the first 10K. From day one I would have to turn the Vox up when I slowed down, when I would speed up I would have to turn the VOX down, not little but a lot. Ten mph makes a big difference. I have a friend that has an 09 Ultra, until two months ago it was bone stock. I have ridden it quite a few times, we trade bikes sometimes when we ride. He VOX operates exactly like mine.
One of the nicer things about the Harley music and intercom system is that the passenger has complete and seperate control of the both the music and intercom volume. Unfortunetly, you lose the ability to control the music volume if you are in the intercom menu. If we are traveling a back road with a lot of little towns, I have to leave the radio in intercom so I can constantly turn the VOX up and down. 35 mph and the VOX won't key off, so I turn it up about eight notches, 55 mph and the VOX stays on constantly, so I turn it down eight notchs. Over and over.
We like to look at old houses as we wander through small town America. When we are on the Wing and come into a small town, one of us will turn the mikes on and they will stay on. When we leave that town, one of us will turn the mikes off, all with just the tap of a botten, without even having to take our eyes off the road. I would rather have that control on the Harley, instead of constantly having to look down while I run the VOX up or down and having my wife having to ask why her music volume isn't working, again.