I agree with the 6 month shelf life of Hopes, I must have had about 10 Hope mono trials now and they all were great for a few months, then just go downhill and changing pads, rotors, bleeds would make never them work as well as they did when new.
As for the Marta, Stan had one on the front of his bike and it was pretty good, one of the most powerful brakes I have felt actually. I think he's had a couple of leak issues but Magura seemed to changed them for him. The only thing is that Stan never really falls off, after a year of riding his rotor still didn't rub, so I can't comment on their strength.