It works in all E-ZPass states, as well as GA, NC, & FL. Is your state not part of E-ZPass?
E-Pass is functionally equivalent to SunPass. The only differences would be which website or app you use, and how you add funds. E-Pass Xtra adds E-ZPass interoperability, which SunPass does not currently offer. E-Pass Xtra costs almost as much as the SunPass portable,
E-Pass did recently upgrade their website, but it still may not be as smooth & spiffy as SunPass. I think I read that they also recently introduced an app, but I haven't tried it.