Wait... I'm lost. I thought the dance merely let you move and get your full attacks. not get extra attacks based on distance. Though it is interesting for a character with speed in the triple digits to move half the distance, slap the enemy, and then run back to where he/she started.
The character doesn't get extra attacks. A Dervish doing a Dance is able to make a full attack, but must move at least 5 feet between each attack. Strictly by RAW, it looks like that means he must do a main hand hit, move 5 feet, then do an offhand hit if available. Kinda annoying really.