Since you didn't mention a specific enclosure, I can only comment in general...
The only part of the enclosure that is of concern is the firewire bridge board. As long as the bridge board meets the requirements for firewire (or IEEE-1394), The it is for all intents and purposes, OS neutral.
On your Mac, there is no drivers or software that needs to be added in order to access and use a Firewire enclosure. However, some vendors have utilities they include, and in most likelihood the utility has never been updated since 10.2.whatever, hence the statement, "up to".
As long as it is firewire complaint, I wouldn't worry to much.
Now as to my own preferences, I like bridgeboards that use Oxford semiconductor 911, 912, and 924.
So, which enclosures are you looking at?
Tom N.