I just upgraded from 3510 to 6100 and thought I could easily switch the hands-free installation in the car by swopping over the phone-holder thingie. Not so simple, of course. Oh no. You've got to buy new car kit, sir, the HFU-5 box under the dashboard won't do at all, it's the HFU-4 you'll be wanting now. Can't just sell you a simle cable, sir, no, gotta be US$ 200 of new kit, sir, thank you sir, yes we do take plastic.

Anyone else had this experience? Is this really necessary, or is it just wringing so much more cash out of the customer?