I've just begun experimenting with creating a submixed reference track within my projects when they start to get heavy in tracks and plugs. That way, I can mute all other tracks and use the reference to lay down my remaining tracks. Seems to work well so far, but have noticed that when I unmuted my drums to be certain i was lined up, that my cymbals had a ever so slight phase to them. As if there was some minute delay between the reference track which includes the drums, and the actually drums tracks. I don't think it's significant enough to translate into a tracking problem for newly laid guitar parts and such, but wonder about the implications when it comes time to add more and more to the project. Any thoughts??