It takes a very good non-hydraulic disc brake to impress us, but Avid manage it with the latest iteration of their BB7 mechanical brake.
Other than a smidge more modulation – something we actually like – and a bit of metal cable ‘feel’ though the lever, you’d be hard pushed to know that you were on mechanical rather than hydraulic discs in performance terms. We were impressed at being able to 'feather off' speed or dive deep into the lever with the stock sintered pads.
Early mechanical disc brakes were heavy and mostly inefficient; not so the BB7. At 329g per calliper they’re about the lightest available, and with ‘dial in‘ brake pad positioning you can set rotor clearance in a matter of seconds. Which is useful, as you will need to do this regularly as the pads wear out.
You'll also need to routinely lube the cable run to minimise cable drag – especially in wet and grimy conditions – to ensure smooth running; using Teflon/Gore-Tex sealed brake cables is a good choice. The BB7s take the same pad shape and mount fittings as Avid’s Juicy models, so spares are easy to locate.