Advice: Verizon TP2 in Ecuador?

I'm currently running the excellent and fast Mighty ROM on my Verizon TP2. I'm thinking of going to Ecuador. I hear they use "GSM-850" networks with SIM cards. I've heard that MightyROM won't work on GSM networks.

Should I unlock the SIM card and flash back to the stock ROM?
Are there fast GSM-based ROMs that should work in Ecuador with a SIM card purchased there?

Thanks in advance!