The AB6 is very similar to what a domestic first class would be. I have flown this route from CMB-BKK before (arrived via Sri Lankan) and because of the night departure I can't imagine you will be too bothered by the lack of comfort. There is a community screen and average recline. Food is served quickly after takeoff as opposed to before landing which does cut into sleep time but all in all it is certainly nothing to complain about. CMB is a cool city but it feels much more natural to fly out on an old A300 as compared to the new A340 I came in on if you know what I mean.