We just swapped our old removeable transponder with battery with new one with RFI chip. Only difference is you do not get beep when you pass through reader. If you pass through ez pass toll booth you can see it does register. We have both the truck and fifth wheel listed on account. System seems to know when the trailer is attached. Last week when we were travelling on FL turnpike we were charged for the truck only rate when we went back and forth to Homestead race track from where we had parked 5th.
I have it set for auto replenishment when amount gets down to $50.00. Good to hear about NC. not sure where they have toll roads, but will have to remember to hang transponder on windshield when there.