Feeding live is fine, just supervise the feedings: no leaving a live mouse/rat in with the snake unattended. I wouldn't think the snake would refuse a live feeder if it takes f/t fine.
Personally though, all but two of my snakes eat f/t and it's my preferred feeding method (those two just WON'T take f/t). Just a lot easier for me: I can buy in bulk and just just de-thaw, warm up, and offer. I've read some snakes get "stuck" on live and have a hard time going back to f/t so if your preference is f/t I'd stay with f/t.