I am really into listening to my music when I ride, more then I thought I ever would be. I have upgraded the speakers and amps with the best I could find (Focal KRX2's in front, Focal 7X10's rear, 2 Arc KS125.4 amps) it it does sound great but don't really know any other system to compare it to as all the bikes in my past did not have systems. Reading a story online a couple of days ago someone was saying that they had a similar setup and then changed their head unit and the difference was night and day.
I called my shop that did the original work (amazingly clean install on the 7X10 rear Focals) and I do trust them and he thought that I would definitely hear the difference and knowing me (very picky with Boarzilla pipes, a full face helmet and quick to bitch if after its done I don't hear that much of a difference) thought I would think it was worth it and be happy I did it. Though of course I don't just want to throw away money, this is my only toy and I have never regretted so far doing a expensive mod when it makes a big difference. I am probably more concerned about the look of a aftermarket stereo in my bike. I do know in the "car world" that changing the head unit to a high dollar model will completely change the sound. My shop recommends the top of the line Kenwood (don't know the model #) as they do many bikes (some crazy over the top systems) and he was pretty adamant about that one working the best.
As always I would love to get the opinions of all of you and maybe someone that has already done it?