can you match an SI drum beat to an audio clip?

not easily in MC5.  in Sonar you can use audio snap to stretch your audio to match a steady beat against a specific MIDI pattern.

audio snap is a feature you don't get with MC5, tho, so you would have to do it by hand.  if you played the guitar part against a metronome, it will be much easier to do, but if you played it free then it will take a lot of work to try to line up the drum parts manually.

the way to add a drum part manually is to insert a MIDI drum track, use SI Drums for the output for the best sound you have available in MC5.  open the PRV for the MIDI track (if you don't know how to do that, check the help files for "PRV").  then use the mouse to click in drum hits.  you'll have to play a portion, clicks some drum hits, play it again, realighn the ones not on the beat with the guitar by moving them with the mouse, play it again, then repeat this process until you have all of the hits lined up for that small section, then repeat the entire process until you have the whole song done.

that's a very painful and slow process.  it's much easier to record the guitar in MC5 using the metronome or by laying down a MIDI/SI drum track first then playing the guitar against that.

Yeah, I have to agree.

It is common practice for me now, to always pay attention to the timing... (BPM) and set up the drums first, even if it's just a snare/kick all the way through so I can keep on the beat.

I also insist that collaborators follow certain "rules" to make the collab easier, and the main thing is record to a metronome or timing track.

Trying to fix it after is harder, much harder than doing it right to start with.