Let me offer a different opinion:
What is it you ultimately want to instruct? If it is ME/IR instruction, I would go for CRI (ME) + IRI ratings.
The reason: If you go for the FI rating, you will need to get the restriction removed, which can be a bit of a problem, before you can do the ME and IR bits. If you work part-time, that can take a loooooooong time.
If, on the other hand, you enjoy turning pedestrians into aviators [as I did], go for the FI.