I am very compelled to share this information.
I stayed at SJ Mabul dormitory for 3 nights. On the first 2 nights, I woke up with severe itch on my legs, arms and shoulders. I asked to switch beds, at which point i SAW a dead bedbug on the new dormitory bed!! I went to the Resort Manager to show/inform her of the bed bug situation. She expressed very little compassion or empathy - she said to me "we deal with this everyday" - well if it was dealt with, there would be NO bedbugs. She also told me that that they will look into it. Well, a few hours later, I met a girl who was assigned to the same bed that I had slept in. So much for taking this issue seriously.
I had also seen a bedbug at SJ Semporna dormitory. Luckily, I saw the bedbug before I slept in the bed so I had a chance to run out of there. I should have known that SJ guests go back and forth from Semporna to Mabul locations so there would be no escaping the bedbugs.
That issue aside, the resort itself was maintained well and the diving schedule was organized quite seamlessly. The food was ok. We were fed the same rice, noodle, and vegetable (diced carrots, peas and corn) dishes everyday, with a slight variation in the meat dish. The coffee/tea was available all day which was nice, especially coming back from the dives.
NOTE: for the 1:30pm lunch, be there ON TIME. There was never enough food because the day trippers also stopped by Mabul for lunch. Fruits and meats were gone in minutes.
Divies in Sipadan was amazing. Incredible. Phenomenal.
Dive sites around Mabul were nice, but Sipadan is a must!!! It's a completely different world at Sipadan!
I would definitely recommend staying Mabul for diving Sipadan - but save yourself the misery and do not stay at SJ