My new Vanishing Point arrived with an M nib, which is a bit too THICC for the note taking I want to use it for.
I tried swapping for the EF nib in my Majohn A2, and they seem to be a perfect swap.
It got me thinking I might order a F from Pilot, and then put the M in my A2 to be used for more fancy writing.
Yes, they are 100% interchangeable. All the parts are, actually. You can even mix and match the sections if you’re feeling perverse; the threads are the same.