black maggies are to forget
Actually when I had it I used it as a horn, as it wous loud enough, but at proper braking you could see people faces
I had a maggie, the pads worn in an angle, they were good green rockmans, the mounts were fcuked, the rim was actually properly grinded
For commuting I could not use it to slow me down, as the wheel locked immediately, otherwise it was just noisy
For trials use, they bit, and there was no god that could move the wheel
I would say give it a go, have a good feel with good pads and mounts, with a fresh grind, and see how does it perform