Judging from SE's established track record with this game, F2P would no doubt suck in the most illimitable sense of the word.
When a popular MMO goes from subscription-based to an F2P model, it is almost always a last-ditch effort to ebb a consistent loss of subscribers (due to being unable to adequately compete). Some games that do this go on to do pretty well with the model, but in this case I think it would just delay an inevitable end... given the production costs and the extreme lack of real content, it seems like the game wouldn't be able to attract/keep enough people to draw a decent profit. How many people right now would be willing to pay 5-10 bucks for an SP/EXP bonus, given the
freaking awful state of end-game content.... probably not that many people
The ironic thing is that the way this game is systematically set up would constitute an excellent F2P opportunity, but since extra classes are not worth the time fully leveling and content is sorely lacking and imbalanced as is, it would just be a bad idea atm.