Here are the results of my testing. All shots were with the 100mm f/2.8L Macro IS pointed at a fluorescent ceiling fixture (i.e. a featureless white subject filling the frame), M mode, f/5.6, 1/100 s, ISO 100, manual focus, all 'modifiers' off (e.g. ALO, PIC, HTP, etc.). Shutter time refers to the duration of continuous shutter press, write time was measured from the start of the shutter press until the red 'busy' light went out. All values represent the average of four tests.
Tests with old firmware are shown, but grayed out. Notice that while previous verisons of firmware don't affect cards rated at 60 MB/s or slower, the old firmware really throttles the faster 90 MB/s card. Also, that 90 MB/s Extreme Pro is UDMA6, and while Canon's firmware updates state, "Improves writing/reading speeds when using UDMA 7-compatible CF cards," clearly they also improve performance with fast UDMA6 cards.
It's interesting that a faster card gives a slight benefit to even the 'slow' 5DII, with one second shaved off the recovery time from a 3-second burst, and 6 more shots obtained in a 20-second burst.