I'm going to a gig tomorrow and thinking of recording, but I don't own a matched pair of shotgun mics. Should I just catch a mono recording? I have like fourteen mics but no two are the same except my drum mics.

I don't get a board feed for this gig.

I do have a figure eight pattern, so I could do a mid side using that and one other.

You could go mono, clone the track, give the clone a 30ms delay and pan the tracks wide.
 
Rocky

Use 2 or even 4 different mics. Do a sound check to get the placements as best as possible and record away.
 
This may have to deal with you also. When my band plays out, every instrument is ran through an analog mixing board (drums, vocals, bass and guitar) and they play out through 2 or 4 PA speakers. We just take the 2 outs into a hard disk recorded, like Zoom. then i can transfer the zoom into sonar when i want to 'fidge' with it.
 
CJ
 

He isn't able to get a feed from the board. I think I would just record it mono, Geoff.

Thanks all! I really appreciate all your responses.

Actually using 2 different mikes would give you 2 different sounds. You don't have to pan hard left & right... You could mess around with the 2 tracks blending with just a little panning and might sound fuller than just one track might have. 

Do what the pro's did in the 80's/90's. Nick an audience recording from another band...

I would record the audience with two mics spaced over a very wide AB spaced pair. (either side of the venue) That will sound way better than that crap of cloning and delaying mono tracks. (people need to stop giving that advice, it is rubbish! That may work in some situations but not this)
 
Don't worry about the fact the two mics are different.  Just try and pick the two closest in sound. You can always EQ one mic compared to the other and get it closer in sound.  You wont hear it so much in the audience stuff.
 
What you will get from the AB spaced pair will be a very wide stereo image of the audience which will sound great.  And being so wide it will collapse down to mono OK as well.
 
Sorry, re read your OP. My approach to audience recording only works well if you are tracking everything on stage from all the mics and DI's on stage as well.  If you are trying to record a gig from the audience then XY co-incident might be the best shot. Matched mics would be better in this situation obviously.  You are not going to get a great recording from the audience no matter how you look at it.

Looks like I've been upgraded. I just got a note that suggests I'll be able to make a 16 channel recording off the board!