Aquanauts used to have a policy that no divers were allowed to dive unless they came with an INS/DMs group or used one of their (aquanauts) own DMs. I found them to be stringently safety conscious because of this and very very well organized. Admittedly I have'nt dove Pattaya for over a year though but thye would be high on my list (if I hade one ;+) ) as their boat is very big and well laid out.