I'm fine with series 8 not starting for so long. I think modern British viewers are spoiled with Who having so many episodes. I don't necessarily expect American cable style number of episodes and I certainly don't expect American-style clockwork regularity of seasons. If it helps stretch the budget, that's fine with me.
60 minutes for the special is a disappointment, though. I personally want it to be two hours. Sure, it would cost more money than a single episode, but I don't think it's even the equivalent of two episodes because you'll save money by having the same characters and sets. Given the long delay for the next season, I wish a bit more money was placed into that special. After all, it'll be a long time before you hit such an important milestone, I'd like the experience to last a bit longer.