I must say I don't really see the sense of getting ATPs. Atlantic Express are already using a couple of ATRs, so getting more of these, this time for cargo, would make more sense from an engineering/spares/rating viewpoint. OK, so the ATR might be more expensive to buy outright, but at least it comes in two sizes (-42 and -72), has a long track record and no maintenance issues - just ask Westair or Emerald - plus there is a decent number of ATR-rated people (both in maintenance and flight deck) around.
Cheers
