Supporting various versions of Cabal

Hello, Is there a story for supporting various versions of Cabal in a package? For Takusen we now have three different Setup.lhs files, for Cabal versions 1.1.4, 1.1.6.2, and 1.2. I'm not sure I want to discard the Setup scripts for the older versions, as this allows users with older installations to use Takusen without being forced to upgrade their Cabal package. However, I'm also conscious that latest Cabal works with versions of ghc back to 6.4 (if not earlier), so is this a non-issue? Is it reasonable to require users to upgrade Cabal to a newer version than the one that ships with their compiler, just to get your package to build? Thanks, Alistair