Had mine this week.
It was unpleasant, but bearable.
Due to the size of the manometry tube, it was worse than the PH test. The only issue is discomfort, not pain, and getting use to the feeling of the tube being in, which took a few minutes. On the pain side of it, it was tube being passed through my nose, sharp pain, lasted less than a second.
With the tube i went shopping, to the pub and other things. Eating gave me an odd tugging sensation, but no pain! I slept really well at night, no concerns there. I did tell my g/f to sleep on the sofa