larryepage wrote:
I think someone needs to do a meaningful investigation and let us know whether there is a speed increase or not...
Below is Thom Hogan's Dec. 5 post on the subject:
"A point or two of clarification on XQD/CFexpress (CFe) is needed. The physical hardware in the D500, D850, and D5 (and Z6/Z7) has some limits to what it can do. While the hardware portion of XQD and CFe is essentially the same, the software stack that does all the work is different.
In making the XQD cameras CFe capable, Nikon is essentially swapping out some embedded and internal EXPEED capabilities (XQD) with some external firmware (CFe), which means that there can be overhead in using a CFe card in an XQD camera. This typically shows up as the buffer fills, reducing in-camera performance slightly. On the other hand, if you use a CFe card in a card reader that's Thunderbolt 3, you'll be amazed at how fast it ingests to your computer, even compared to XQD. So: in-camera performance isn't improved, but ingest-to-computer might be.
But there's more to it than that. Most XQD card readers also have dedicated software in them. You can't update most such readers, so you'll end up needing a new card reader that understands both XQD and CFe. Unfortunately, there are some card readers now that only understand CFe, further complicating things. (And Canon chose to only support CFe.)
The real benefit of the CFe firmware updates (D5, D500, D850, Z6, Z7) isn't performance oriented, it's convenience oriented. It means that you can buy new cards with future potential (CFe) instead of continuing to buy older cards (XQD) with a top end that won't get better. CFe also increased the number of vendors participating, so CFe cards will become more ubiquitous, while XQD cards will slowly go the way of all dying formats and disappear eventually. Still, XQD will be around for awhile, as it's used in some high-end pro video and industrial gear.
Thus, CFe compatibility isn't something that most D500, D850, or D5 users need to rush out and embrace. It just opens up more options, and options that will continue to play in future cameras.
Which brings me to this: the only CFe "native" cameras Nikon has made so far are the D6, Z6 II, and Z7 II. And they're backwards compatible with XQD, thus proving my point about convenience. Nikon did the right thing here, though it took them longer than expected".
http://www.bythom.com/