A passing note. I'm a CRI. By virtue of qualification, experience and recency, I can teach tailwheel, VP, retracts, and microlights - all as differences training. I flew none of these during my CRI course and skill test. The same is probably true of most FIs who can also teach these things.
Just gently shooting down one of the underlying arguments being used.
One another note, I think that we should be careful not to confuse "night instruction" and "instruction at night". They aren't the same thing.
G