I just switched devices. PLUS traffic moved over, but the map and fuel subscriptions didn't.
I understand the map rationale, because the map remains on the old device and it's unfair to get two devices upgraded for the price of one. So I had to do the map subscription all over again (I got 3 out of 4 maps on the old Tomtom so I'm not too bummed out).
It doesn't seem fair that fuel doesn't transfer over, since the info goes stale just like traffic does. I'll call Tomtom tomorrow and see if I can talk them into moving the fuel subscription.