FS 570 '11 or FS 650E '07

I own a 2005 650 with low miles and have just picked up a FE570 2009 model.
Both the bikes are stock except for an auxliary tank on the 650.

I can only sum up by saying that the 650 is the quickest bike I have ever ridden in the dirt and a little on the raw side whereas the 570 is a little more refined and probably gets the job done just as well with less changes of underwear.
The 650 will probably be higher maintenance if the 570 has had the few common problems sorted.
Put it this way the 650 would be like dating "Pink" a little on the raw side, not quite sure what to expect at any given minute but you'd definitely remember the ride for the rest of your life.
The 570 would be like Kylie Minogue, refined, stylish and possibly hold her value a little longer !

Buy the FS650 but it will need a new rod at 200hr, and i would say in years to come a 650 will be worth more then a 570!