I see from Stratics that the paladin spell "Enemy of One" has a specific creature type turning orange. I presume that's a specific npcdesc entry.

I have managed to write all of this spell except for this orange thing.

With 097 can this be done with repsys.cfg and a hook given the bug with a reputation hook exiting?

I am not at my best creating this sort of thing, so if you've done it, some hints would be most welcome.

You could use the highlight color and name color hooks in the repsys (no bugs there) to do the orange coloring.
The bug with the repsys is if you use mobile.SetCriminal() or .SetMurderer() -- it causes the hook to stop at that point.

Yep, that works - mostly.
The enemyofone highlight is the GuildEnemy colour.

The problem with the repsys hook is that it doesn't update guild changes until the mobile moves.

Anyone got a way for force the server to send a reputation change to the client? (eg when changing guild status / allies / enemy guild etc)?

I'm not quiete sure but i think Packet 0x77 or 0x78 could solve your problem there.