I was going to warn about the exact same thing choochooman did. I crossed the bridge on 78 and was charged $10 more when I should have been charged $1 more. Because my ez pass is based in New York State, it took me 3 months to get a refund. As stated, their web site recommends putting the transponder in the special bag do it won't transpond, pay cash and get a receipt just in case it does transponder. EZ, right?
Other than the Deleware River crossings, I've used it towing a trailer in various states and never had a problem.