I actually think the stereo from the speakers is better than the head set. You have no control over the bass or treble with the head set. Very tinny sounding in the helmet. Once at highway speed and the volume comes up with the speed its very respectable. This is on an '03 Ultra.
I have an 02 RoadGlide with the TourPak and Passenger backrest...It has the rear speakers and amplifier and it is very audible. I can hear the music very clearly at all speeds and so can my riding partner if he's next to me...LOL!
I think the system is great...although I am tol that you can upgrade to better speakers for under $100 an it gets better.
I find the stock stero and speaker work well up to about 75mph. After that you have to raise the volume so high it distorts the sound.
I was talking to a couple of friends this past weekend about this issue. One friend installed the HD Stero upgrade kit and packed loose holofill [like the stuff in pillows] behind each speaker. He said the performance was noticable. My other friend just packed the holofill behind the stock speakers. He said it was a definite improvement.
Guess what I'm doing this weekend.....
Also, on longer cooler rides I use a full face helmet with speakers. I find the sound to be good, better than using the external speakers.