OK, here's an update.

The 200 mg with coffee has me up to midnight at a minimum. Full day and then some. Very bad sleep until the next day. Didn't take any drugs nor coffee and had a well needed sleep.

Just tried 100 mg with a coffee this morning and needed to nap today. So that's apparently not an option either. I'll try this again tomorrow.

It doesn't look like Modafinil has any predictable or reliable behaviour for me. This isn't looking good at all.