Wait, how are you getting oily coffee from a Clever dripper? If anything the paper filter should be largely eliminating oils.
It does a good deal, but still has more than drip. Personally I don't mind but I know my wife describes the brew as "oily".
Huh - I brew with Clever Dripper most days and wouldn't characterize it as 'oily' - its definitely got more body than a V60 (my other go-to). I suppose all immersion techniques will give you similar results in that case, with something like a French Press giving you much more oils.
Disagree on roast, I've had great dark roasts. Even for espresso, I'd say full-city / medium-dark is preferable. However, I've had more bad dark roasts than bad mediums.