I just changed my SOny Ex1 for an XF 300 and I am entirely satisfied. From my self opinion, XF300 is more easy to use with more function that are easily accessible without having to go trough the entire menu. Also, all the accessories are way less exepensive. That was the main reason for me to change. Memory is cheap, very cheap compare to SXS cards. But pay attention to select a brand of compact flas cards that is approved by Canon. Otherwise, you will have problem recording files that last more than 4 minutes, wich is not practicle at all.
Only negative thing I have to say about the XF300: not very efficient in low linght condition and way to much dept of field, especially when you pass to this cam from an Ex1.