Hhmm, i personnally cant agree with that my self, i run single speed on dmr revolver hub with an acs, perfect and no hastle. Suppose if you had gears it might be hastle...
If you ever wanted to get into competitions and had a stock, you might have to have gears as part of the rules, but im not really into the comps, so i dont bother.
Its a pain when i want to ride anywhere though!
But yea, like others have said, try both! Good Luck!