Now I wish someone would get a clue and make a dual XQD/CF reader since many of us use other bodies which use CF.
The last thing many of us need is another reader.
I think the difference in terms of speed is around 10% (1000x vs 1100x - these are a multiples of CD read speeds) however I think the real advantage may lie in the use of PCIe instead.
Luckily I use XQD as backup. So I usually don't have to take it out. I use CF as before and use the portable reader to read to laptop. But a reader that can read both CF and XQD will be very useful for many..