Yeah, um... never ... and I mean ever.... listen to service reps... lol.
There are numerous bugs since 4.4.2 released. Bluetooth reporting battery drain when off, LG backup is buggy, auto brightness still crappy, and.some other things.
The 3g/4g switching issues are network related. You can get all the updates in the world and until the network updates are finished its just something we have to live with. They could certainly disable band 26 and 41 on phones that dont have it in their area yet but we can do that ourselves so sprint wont bother.
I know about the eCFSB issues but there also seem to be issues in band selection, in areas where roll out is complete. You can disable bands, but seriously people like us on XDA are few and the majority of phone buyers dont understand all this stuff like why you cant have 4G and CDMA voice call at same time and about eCSFSB. Youll find most people complaing how old phones are better than G2 because the can call and surf at same time and that signal sucks on the G2, not understanding that the old phones were SVLTE and single LTE band.