Wanted to comment on this one too:
RAT5
...but on current B738 F5 non LVO takeoffs: absolutely, the keeping of the centreline until airborne is visual; has to be. The initial rotation is visual. This is the best way to keep wings level under all circumstances and assess the correct rate.
So it seems we are starting to agree too. Visual until airborne.
I like to complete the rotation fully visually and that works for me. If someone want to transition a couple of degrees earlier I won't argue about that.
Of course that goes for any flap setting. My company uses flaps 1 on most takeoffs (I know a lot of airlines banned flaps 1).
Maintaining center line AFTER airborne is something that seems to be largely ignored (as can be seen from lining up behind departing traffic in crosswind). Protected area for obstacle clearance seems to be disregarded.
Doing the rotation visually (and completing it visually), helps in that respect too. And the crossed controls that at being applied during the rotation (rudder to keep the center line and aileron to keep wings level), can more easily be coordinated phased out so that the aircraft comes out in crab angle according to crosswind exactly maintaining the center line.