Ok, I switched to Kris Holm Spirit (Disc) cranks, so that I could get used to them before adding a brake in the future. They do not have the same hole positions as the Nimbus VCX+, so I dropped down from 125mm to 117mm. In my limited testing this seems fine and I think I should be able to get up all the same hills without a massive slow down.
I also weighed it. Now granted I am using some crap bathroom scales and weighing myself and the bike, then subtracting my weight. Using this method I get 6.4kg. Given this is a shitty way to go about it, take this with a pinch of salt but it is interesting nonetheless and seems pretty low considering no carbon rim. Obviously things will change a bit once I add a brake and handlebar.
P.S. The other thing I thought about just now was that it is quite an interesting mix of manufacturers: Nimbus wheelset, Quax tube & tyre, KH cranks and M4O frame. It seems I show no favouritism! 
