I have the Spectron bag, because I was interested in the material. It is very light and pleasant to the touch, as advertised, but I found it is awkwardly "floppy" if it's less than absolutely full. The more conventional materials are somewhat stiffer and hold their shape regardless of their load. The Spectron Maker's bag is so supple that if you have something small, but a little heavy, such as a laptop charger, it's able to pull the material down, which in turn causes gaps where the top flap folds down over the bag, and the flap's locking mechanism does not tighten down enough to prevent that.
I actually carried this bag "in the wild" last week and was not especially satisfied. I could not carry this in the rain without water getting in at the edge of the flap. Now the bag is beautiful and well made, as Tom Bihn bags are. I own a bunch of Bihn products, going back some years, and this is the first one I've wanted to return. Alas, I had taken the tags off and used it (it never occurred to me that I might not like it) so it's ineligible.
I do like the overall design quite a lot, and I suspect that I'd like a Makers in one of the stiffer materials. Were I to buy this again, I would avoid the Spectron. I'm actually not certain how the Spectron version was even released to be honest. I'd have thought testers would say "nah".