I was in the same predicament a couple of years ago when I was waiting for my Field (graduated blue with gold leaf mountain contours). I think the decision making process has a lot to do with where you live and how you like to ride. I love climbing so wanted something that wasn’t too heavy. Having raced the Downhill mtb series here in Japan I’m a reasonably confident descender . I finally decided to go with rim brakes and have not regretted my decision. Here in Japan the weather is pretty predictable so I rarely get caught out in rain.
As you said you are moving to London soon, I don’t think weight would be a huge concern as the longest climbs are more like bumps compared to those in the alps or in other parts of the world.
I don’t think spare parts will be a major concern for at least 10 to 20 years.
Personally, if I were living back in the UK I would be tempted to go disc due to the the crappy weather and lack of big climbs.
What’s the ETA on the Field btw? You are going to love it. They ride as smooth as butter that has been left out of the fridge for a few hours
