In reply to UKC Gear:
It might not add much to the review, but I've had mine for a couple of years now and - price aside -can't really think of anything I don't like about them. I suppose I'd also be a bit reluctant to use them for lots of mixed torquing, but probably due to the cost more than any worries about robustness, and Grivel do make a specific sturdy blade for this sort of thing (which I've not tried, so can't make judgements about their durability).
My slight regret is that I got the Dark Machines before being able to try the Cortex (Cortices?). On the other hand, it now feels like they were a comparative bargain...