I do not own either BGEE or BG2EE so I cannot test this at all. The parts that I know won't work on BG(2)EE, like the starting XP fixer (which patches the executable) will not install on a BG(2)EE game.
The creature-, mage/thief- and quest XP fixers should theoretically work on BG(2)EE (or any IE game for that matter) since they are written as patches, unless the EE games introduce new ways of gaining XP that these patches don't cover. The mod covers creature XP, the xpbonus.2da table, the xplist.2da table, dialogs and scripts that use the AddexperienceParty() or AddXPObject() actions and spells that use opcode 104. (Come to think of it, items could use opcode 104 too. Perhaps I should look into that. Does any game or mod implement something like the Libram of Silver Magic or the Tome of Exalted Deeds?)
I only tested this on vanilla BG2 (with ToB and G3 Fixpack), BGT, and vanilla BG1 (installs with warnings on the latter). If anyone wants to go ahead and test it on EE, or better yet, patch it to work on EE, I'd really like to hear about it.