UOp is also pointless and is also not 'supported' by mIRC in the way of events. Halfop is somewhere near useful and is present in many IRCds.
StriderGU - Well for admin there is an actual (undocumented) on ADMIN event. For the others you can use rawmode to detect when one of those modes is set/unset and as MonoSex said, $nick(#channel,nickname).pnick to detect whether that mode is already present.
