Originally Posted by
ThermionicScott
It all depends on you. If your bike falls over or you crash, do you:
A) check rear derailleur alignment and shift through all of the gears while off the bike, or
B) just hop back on and ride
If you're the type to recheck everything, you may be able to do without a dork disc. If (B) describes you, definitely keep it on.
This seems like the most sensible advice so far. As far as aesthetics are concerned, and providing you are not (B) from above ^^^, I think the only time they look good is when they are the metal 'pie plate' variety and only on vintage bikes with perfectly horizontal top tubes.