Why cant the the achievement/medal data from the flash be uploaded to NG as well? Every time I close the game and open it again, I seem to lose all my progress including achievements/medals and unlocked characters :(. (Although completed achievements/medals are still on the "medals" bit.
There's also the risk of people copying achievement/medal data from the local files to each other... I don't know if/what measures you have to prevent this, but look what happened to TF2s achievements...
I think the fairest way is to implement them to game devs would be a screening system for games with achievements/medals could still be voted on and blammed/protected, but if protected they would go through a screening process where a moderator would determine if the achievements/medals were fair and suitable, then the people who earned the achievements/medals would get their points and things would carry on as they do with Portal Defenders. That is, if you were planning to implement them as a site-wide stat... I'm probably not explaining it very well, but that's my point of view.
Also, are they called achievements or medals? The flash calls them achievements, the site calls them medals...