Illinois I-Pass: Only commercial vehicles need the "blue" transponder. Private vehicles, with or without trailers can continue to use the white ones. My fifth, as well as a big rental truck, all had no problems anywhere on trips from Minn to New York this past year.
Here is a map of what state accepts what system:
http://www.e-zpassiag.com/about-e-zpass/85-mapNote that Minnesota, for one, is not on there. Our system is incompatible with anyone else's (of course!) - but it is only for express traffic. You can still drive the same roads without toll, but you may be stuck in traffic a bit more.
We went with the I-Pass for trips "out East" after having our NJ EZ-Pass driven to zero by monthly fees. It pays to check each states tollway site. Sometimes they run "sales" to encourage use. We missed one that matched up to $50 for pre-depositing $$ in an account.