I have recorded a few live shows, I used a friends MX that had the digital card connected to a DM-24 console. We would split the multicore from the stage and record all the stage mics via the DM-24 to the MX.
The best way to limit media too slow, is to freshly low level format and initialise the drive(s) you are using.
Ensure that there is plenty of cooling around the drives extra fans pointed at the drives or MX if internal.
Record in tape mode.
Turn off the "Menu 570-Waveform Record" (this came in with OS 3-11) as if this is on it taxes the ram memory when recording lots of tracks, I leave it off all the time, it is only the wave graphic file being drawn not the actual recorded wave file, the waveform is drawn when stop is hit at the end of the recording.
When recording live and you hit stop, depending on the length of recording it can take a few mins (maybe even 10 or 15) before you can record again, I usually record a whole band set before hitting stop, make sure they are not going to rush back on for an encore, if this is going to happen leave it recording.
Have the MX plugged into a UPS it won't be the first time a band member has pulled all the power plugs at the end of the set so they can pack up, if the power goes off before the mx has finished writing data, goodbye show.
Cheers
Alan.
Just to add a bit here, if you are using mx view, which I would recommend, when the recording has finished, as soon as the recorded files turn from solid red to solid black you can create a new project (don't forget it will set the start position of the new project from the playhead position), the rest of the time the mx takes is only for writing the graphic files of the waves. Be aware, next time you mount the project that if the wave graphics have not been written before it will do it when mounting, only the first time.