Well, if you move to Devon you'll have no option but to get SKY. NTL aren't down that far. My parents live in cornwall and I don't think NTL or Telewest have heard of that county!
Just chill out until you get down there. If you get it now you'd have all the hassle of arranging for it to be moved etc. I can tell you that there isn't much more on Sky additional to what they have on NTL, well, nothing worth having. The only thing better is the fact the red button isn't redundant and when sky set themselves something to do, it usually appears and roughly when they say it will.