I've flown some stuff where I needed to put the nose down to get 30 knots!
I'm afraid that I'm very old fashioned - I write town engine start, brakes off, take-off, landing, brakes on, and shutdown time.
I then log engine time in the engine logbook, brakes-off to brakes-on in my flying logbook, and whatever is in use in the tech log.
GPS is nice, it gives me a cross check that I didn't make any stupid mistakes.
G