People who know a lot more about it than me have made important points on both your threads and I don't disagree ... but ...
I'm in my fourth year of my PhD and I've done the whole thing a four-hour commute away from my university. It was a really good way to do it and I strongly recommend it - so long as you push yourself hard to get a community of people around you. (And it will only work in certain subjects, obviously, but that's a given).
The positive side is that if you do your PhD the traditional way (which you're not anyway), starting out behaving a bit like an undergrad and getting to know other people on the course, it can take a while before you get pushed out of your comfort zone at conferences. If you don't, you have to treat it like a job and you have to get good at making contacts when you go up to your university, and at getting to know people in your local area too.
I've ended up with two research communities that feel like 'home', and that's really useful. Especially because I get to see how different universities do things. I actually attend seminars at two universities and friends I know have found lots of universities are very welcoming in this respect - if they're holding a talk, from their point of view, bums on seats to show the visiting speaker how popular they are, is a good thing!
The downside is that you have to have money and organization to get the teaching experience. You might be able to do it in a day's round trip if you're lucky, or you might get very familiar with the local youth hostel (or befriend people early on who have spare beds!). It is doable though. Same with training days. The thing I regret most is that I didn't go to more of those as all the ones I made it to were excellent.
Final point - yes, I know it matters far more who your supervisor is and whether the department is the right fit for you. But it is really obvious, in my field, that if you were at Oxbridge you are much more likely to land a JRF and finish in three years. There are also differences beween thesis lengths that matter if you're an arts student. At my university a thesis can be 90-100,000 words. At my friend's, it can be as little as 60.
Sorry, I'm rambling on ... I totally agree with others about the postdoc stuff, from where I'm sitting (in the middle of applying), the idea of not moving just makes no sense. But I did want to post because I think long-distance PhDs can be really good experiences.