I have had and used autocom systems for around 5 years.
We had a system on the VFR that worked okay, but not brilliant. The main problem was the volume just didn't seem loud enough. Above about 70mph and we couldn't hear each other. I therefore chose to let it go with the bike when that was sold.
When I got the 4S I looked into this again and brough the middle of their three units (smaller than the top of the range but does everything I want).
It is permanently wired into the bike and takes its feed from the rear light circuit. The box is stuck with double sided tape to the top of the abs pump (replaces the underseat storage tray near the shocker on non-abs bikes).
Because this is a later generation than the original one we had, we had to upgrade the headsets too.
I have to say, the fitting of these into outr helmets was the reason we were getting poor volume levels.
The placement of the earpieces is critical as 15mm off centre seems to drop volume by as much as half !!!
The second time around we took great care in putting the ear pieces in the helmets, plugging a cd into the intercom, and moving the ear pieces around to get the best location before fixing them.
I should add that I fitted both systems so this was entirely down to me. They will fit them for you if you request it, although I'm not sure on cost.
So, would I recommend them ?
Yes. Money well spent.
There are times when the intercom is a pain, but it far outweighs the time it is useful (extra set of eyes looking for road numbers, signposts, hotels, pubs, etc). We can hear each other clearly well over 100mph. Screams from the pillion about 140 just start to get drowned by wind noise (Arai RX7)
We have the pair of leads come out of the front of the seat so I can plug us in while on the bike. When I'm on thebike on my own I lift the seat and they just lay under it out of the way.
Hope that helps.