The class would be more useful if the fn "recognized" additional browsers, especially if it were deployed on a linux-oriented website.
chromium (distinctly separate from Google Chrome)
iceweasel (distinctly separate from firefox)
iceape, icecat, gnuzilla, k-meleon probably don't have enough market share to merit separate recognition... but it might be useful to separately recognize some of the "minimalistic" (elinks, dillo, hv3, links, links2, netsurf) browser b/c we likely want to differently handle requests from those users
For a given use, How old is OLD?
We can parse the version info without the need for the-another a class method, so what merit, what new functionality, does this fn offer? As is, nearly none. Perhaps have the fn accept args, so that minVer can be passed in. Incidentally, what changed significantly b/t ff v3 and v4? I recall a HUGE change between v2.20 and v3, but not much functional change (breaking addons) when v4 emerged.
What I've mentioned above still only addresses the desktop user audience.
For use with a site serving tablet / mobile users, more highly granular useragent "recognition" is probably essential functionality, beginning with, for instance, 'Safari iPad' => 'iPad'