Is WiFi on the F800EXR of any use?

You might have misread my comments.

Just as hardware devices all need driver software to communicate with their host, so a wi-fi SD card needs software installed to allow the card to correctly communicate with the host.

Once I worked out how to get it to work it was fine.  Up to that point I was ready to send it back and claim a fail.  I'm glad I persevered.

I have only used mine once and it didn't fail. I connected and reconnected several times on Android and Windows 7 without problems.  I tested it after removing and refitting several times to ensure it could handle a "cold start".

I might never use it again but it's ready to go if I need it.

--
Cheers
Trevor G
Silkypix tutorials at: http://photo.computerwyse.com