There's only one version of it, so just try and find the most recent firmware. I'm thinking about removing mine from my Wii since there's not really a point in using it anymore, now that
Nintendont is working so flawlessly
WRONG!!!
There at least exist 2 different revisions of the WODE:
1.) The very first WODE had "Wii" and "Wii_Power" labeled on their lower right corner of the main PCB instead of the most common one, which reads "Host" and "Host_Power".
2.) The very first revision of the WODE might run "BOOT Ver: 1.00" instead of the common "v1.01". Check the "ABOUT" menu of the WODE.
Aside from the labels, the very first revision might run a MX25L6405MC-20G SPI-NOR flash which is max. 50 MHz in speed against the very common MX25L6405DMI-12G used on the "HOST" labeled WODE.
Even the RAM between these two revisions might have changed:
The "Wii" labeled WODE might run a MT48LC16M16A2P-75 IT: G while the "HOST labaled WODE" commonly runs a MT48LC16M16A2P-75 IT: D instead. Their difference inbetween is (at least) "Standby current", "Self-refresh current", "Operating current" and "Autorefresh-current". Maybe there are more differences between these two RAM types. At least their size is equal.