UBBCentral is the OFFICIAL UBB website, HOWEVER, Groupee (the UBB Owners) do not provide support for any sites operating with modifications (as modifications themselves at times can be causing some issues in forums).
UBBDev has been around for a long time operating by UBB users versus the UBB owners (groupee).
As for sugguesting FireFox, I myself am not doing so, I've simply helped state that a lot of modern browsers have spellchecks built into them.
