The problem of using custom firmwares is that probably cant use either Garmin official support for firmwares or Webupdater, Mapupdater etc . How could it go with warranty if Nuvi doesnt start or is bricked if something goes wrong with these firmwares?
Better to use Carte Blanche and for Romania CNE IMHO.
I wouldnt use a map cant be read by an official Garmin firmware.