By way of an update, I've received a response from Sky Arts, reading:
Unfortunately, we don’t have The Devils in license in any version – directors cut or otherwise. The non-directors cut version has been shown on BBC2, Channel 4 and on Sky Movies in the past but never on Sky Arts.
So, back where we were. Not sure where Broadcast Magazine got their information from, but a great shame.
I suppose there is a good chance the Lucida Hell on Earth documentary will get shown as part of the package of programmes Sky Arts have bought, so a small crumb if nothing else. Here's hoping Sky Customer Service got it wrong...
Incidentally, does anyone know exactly what footage was found when Mark Kermode/Lucida came across the fabled cans of cut material? Hell on Earth mentioned two complete assemblies of The Rape of Christ plus showed excerpts from Sister's Jeanne's masturbation with the tibia, a bawdy pantomine in the sqaure mimicking the events in the abbey (I always wondered what the full context of the stage was alongside the stake and this revealed it brilliantly) and a couple of shots of debauched nuns (including the big dog lying alongside them, which I always thought was myth until seeing it). I was lucky enough to be at the screening at the NFT a few years ago, but that only managed to include the rape and masturbation scenes, not any of the more incidental, but just as fascinating, footage.