You can tell if a c200 or e200 is a v2 by looking for three things:
1) The packaging mentions Audible support,
2) The firmware is 03.XX.XX,
3) There's a very small "v2" printed on the bottom right corner on the back of the device.
Also, what you heard about getting a v2 to run Rockbox by downgrading the firmware is utter nonsense. The hardware inside the v2 is completely different to that of the v1. Therefore, a new port is needed to get Rockbox running on the v2 Sansas.