I nearly exclusively record bands to click... even if that means mapping the tempo with different speeds for different sections. Here's why:
- comping, it's much easier to put together a great take if everything is in the same place each time
- editing, most commercial records are using beat detective/flex time to quantise the drummers... this means tightening up the performances. You'll be hard pushed to find many rock records where this isn't the case to a certain extent
- programming, more and more bands are using tracks live or wanting to add synths/loops to their recordings... it's much easier to do this if you're using click
- copy and pasting, believe it or not people DO copy and paste... often backing vocals on chorus' etc.
- delays, it's much easier to get all your delay times sync'd with click. A lot of guitarists can input BPM's on their delays pedals or I'll add a delay sync'd to my DAW's tempo.
Hope that helps mate,
Tim