I know that the space requirements for upgrades are contained here:
but it would be useful if you could also list the expected growth post-install.
The article above was identical for the v11 SP10 upgrade, but post-upgrade there was actually a small decrease in space used on the clients and these requirements appeared to be an overhead needed *during* the upgrade. This led to weeks of having the change request denied before an issue forced our hands into implementing the upgrade (and I'm experiencing the same thing for the SP11 uplift). If I could have the post-install sizes available, I'm hoping I'll be spared some of the pain :P