Well, I've taken the plunge and just bought a Hughes & Kettner Switchblade 50w combo off Ebay. It cost me £600 which is more than I ideally wanted but it's in mint condition and as it has most of the effects I use built in, I can offset the extra cost through the sale of most of my pedalboard.
I liked the convenience of a multi-effects but ultimately I just couldn't give up on real valve tone completely. OK, so you can argue that the Switchblade has a good chunk of digital technology in it but I still think it sounds more convincing than any amp modeller as it is a proper valve amp, just with digital effects and midi control so I think I'm getting the best of both worlds. I can't wait to get it :)