I have them and love them. I have a very narrow heel and the Salomon F series are the only boots I've found that fit right. They have a very secure heel pocket.
They run small for snowboard boots. I generally wear a 10.5 shoe and have 9.5 F20s. I figured they'd pack out a little and be perfect. They haven't packed out at all with almost 20 full days in them. I don't think they're going to at this point. I wish I had gotten 10s. They're also nice because they're very low volume. If you're borderline having to get a wide board, you can probably ride a regular board with F20s.