When I ran cable discs (BB7’s), they were much more faff to keep well maintained and running sweet than hydraulics. They were OK to begin with, but once they start to get a little bit of wear in the mechanism, they are a pain.
The real issue for me was the need to manually compensate for pad wear. One particularly wet peak district ride, descending off Kinder, the rear pad wore quickly to the point of the lever coming back to the bars. No more back brake. So, hauled on the front to stop and adjust. By the time I was slowing down, the front lever was back to the bars, and I only just came to a standstill. Once stopped and pads adjusted, they were fine again, but come the bottom of the hill, they needed adjusting again.
You may consider them simple in that you can see what’s going on, but I do find them a pain. Crude aswell – what with bending the disc over to contact the non-moving pad, or running the static pad so close to the disc then anything other than perfectly dry conditions caused crap to rub.
Deore M596 would be a much better option IMO.