I got my DCS 420 (s/n 2475) with Elpac charger and complete manuals today. Battery seems to be in good shape and the unit seems to work perfectly. Luckily the camera has 98-version of the firmware so I tried 5 different CF-cards with Sandisk PCMCIA-adapter. All cards were first formated with DCS 760.
Sandisk 1 GB 2003: E7
Sandisk 256 MB 2003: E7
Viking 128 MB: E2 after the back goes sleeping, so I have to disconnect and reconnect the card in order to take photos, quite annoying. However I can take several photos in a row if the camera stays awake between shots.
Lexar 8X 16 MB 2001: E7
Canon 16 MB by Sandisk 1999: Works just fine, could be a little bigger though.
Next mission is to find a decent sized CF (128 MB) that would work without E2-warnings.
And yes, there are some photos with 420 and AF-s 17-35/2.8 here
Waiting for the summer for intensive infrared testing...