Richard,
I can definitely see the merit of the winddatalogger.com device that you found. It's amazing what's out there waiting to be discovered -- reminds me of the serendipity of my finding otherpower.com right about the time I needed to augment my PV array with a wind turbine generator.
I found a write-up on the AAG weather station unit (originally in Sensor magazine, apparently). A copy of the article has been placed on one of my servers:
Sensor mag article
If using the Linux software (One Wire Weather / OWW), any 1-wire type sensor that is on the 1-wire bus can be logged. The AAG weather station comes with sensors for wind speed, direction, and temperature. You can purchase other sensors (barometer, rainfall, etc) from AAG and other sources.
The author of the OWW system, Simon Melhuish, wrote this interesting report:
Monitoring the weather with RISC OS
For more info about OWW: OWW web site
As for that bearing design that you mention, the AAG unit is very simple, perhaps even crude. It would be a simple matter to retrofit the internals if necessary.
Kind Regards,
ConoHawk (Mark Conover)