I noticed an improvement, not a huge one, but it feels more confident and does less dancing to get there.
It simply is not going to equal the 100-400mm 2 for AF speed and accuracy. I too am shooting them side by side, and it's just not going to happen. The Mk2 is one of Canon's fastest best focusing lenses in existence. It beats pretty much anything you put it up against.
That said, this is one of the best 3rd party focus set ups I've come across, and considering it's doing it out at 600mm with a tiny f/6.3 aperture, it is VERY impressive!!
Yo Jake - I think you have an addendum to make in your gear list still