I have a baby enchi that is stuck on live. The breeder had her to F/t and then she didn't eat it one week so he gave her live and we haven't been able to get her back to frozen. that being said I have been luck enough to switch a few of my snakes over to f/t from live. You might have luck if your snake is young enough but none of my adults that have been eating live for 2+ years will even look at a f/t let alone eat it.
f/t is for sure easier, even if your gf gets creeped out by it. its cheaper, easier and if your snake refuses it you dont have to have a cage for the mouse till next feeding day.