The difference between the two isn't quite as drastic as the difference between Limit and No Limit but it's definitely a different game overall. On a 6 max table your odds
take a major shift and your starting hands requirements must accordingly shift. The major problem with this is that you will find yourself going up against stronger on a more regular basis and because of previous investments and/or your belief that your opponent is bluffing or semi-bluffing you will find it much harder to get off of a hand.
There's more that goes into it besides what Stan and I have pointed out, but for my money I'd have to say that's enough reasoning to steer clear. If you are already playing it and if its has been your primary game for most or all of your poker life you will probably have some issues coming off of that mindset when you play FR because you are probably well suited to playing a wide variety of hands. GL either way.