I can so empathise - I'm in the process of re-writing following a failed Viva and I'm really worried about the same thing happening to me. My external seemed really negative, and I'm not sure anything I revise will be enough.

I'd take the MPhil - it's better than nothing.

I've also been thinking about going to another University, but I suspect the regulations say you can't submit it for a PhD when it got an MPhil somewhere else. Unless you just don't mention it??? But then, you'd always have the worry that it might be taken off you at some point.

I was going to go for PhD via publication - but possibly in a slightly different area as I don't think I could get enough publications out of my PhD, such as it is.

It could be worse, keep trying :-)

I'm currently struggling with theoretical frameworks - my supervisor never mentioned it, but at my Viva it was one of the things flagged up, necessitating a re-submission.  The odd thing is, I thought I had a theoretical framework - with having included theory, on which my hypotheses were based. But clearly my idea and the external's idea were completely different.