The V2 gateways are fine. I have just deployed 18 of them...
I am, however, working on a way to have them automatically reprovision if we change what extension is connected to what port on the device. It currently seems that you need to factory reset and wait a few mins for the device to start again and read the new extension assignment from the 3CX config. It will probably be a tweak in the template so no biggie as we have to use a custom template anyway to change some defaults on 'Loop Current Disconnect' timeouts so that calls are properly ended on the old analogue handsets.
Cheers