Hey all, replying to the few comments about the Sub EQ.
Generally once I've EQ'd the Sub on the root frequencies I won't do any further EQ during the chord progression section. I understand that sometimes the Sub can become a lot louder or quieter in certain keys - to combat this you can add a compressor to the Sub AFTER all of your EQ processing. Use the Voxengo Span to identify which chord progression increases the volume of the Sub, and try to make sure the compressor is compressing by a few DB at that chord only.
You could also try what other people have mentioned: render out the Sub to audio and then apply additional EQ (dips/boosts on the correct frequency) for the different chord changes to smooth it out. However, I sometimes find this makes the Sub sound a little inconsistent.
When the Sub is put through the Kick & Bass bus, the 2x compression on there will also help to smooth out the Sub chord changes. You'll notice in the track there's really not a massive difference in volume during the chord sections.
Unless there is a really huge difference in volume over the chord changes, I haven't noticed it being a big problem when playing my tracks out live. As long as the chord changes are consistent within a few DB, then they will sound fine on the club sound system.
Also, remember that your speakers/studio room can effect what you're hearing. Certain keys will produce more "standing waves" or bounce around your room in funny ways. For example, my room has a noticeable increase in volume in the keys of G.
Hope that helps 
James.
