Hi Aussie Shooter.
I have been using these, Kingston 600x http://www.ebay.co.uk/itm/Kingston-16GB-CompactFlash-CF-Card-600X-CF-16GB-U3-for-DSLR-Camera-GOOD-USA-/322410907744?hash=item4b11300860:g:Qg0AAOSwux5YXWh6
but they have been discontinued and are getting harder to find.
They have a lifetime warranty and I have several of them, I have had a failure, after reading the files off the camera couldn't find it, Kingston replaced it without any problems but only had these to offer, 64GB 266x http://www.ebay.co.uk/itm/Kingston-64GB-Compact-Flash-Ultimate-CF-266X-45MB-s-64G-64-G-GB-Life-Time-Warran-/322297965855?hash=item4b0a74ad1f:g:0p8AAOxyOalTZxZr
I wasn't keen on the loss of speed 266x vs 600x but I think it still qualifies as UDMA.
I did a quick and dirty test, took a series of raws on full speed until the buffer filled up and slowed down the camera then four more, I did this for both cards and the 266x actually cleared down the buffer in less time. It was the same number of shots.
I can't tell you if it is any good for video.
Hope this helps.
Cheers, Graham.