On my recent trip to the Philippines, only one day, at Apo Island, was the visability good enough to use the 150mm. All other days I needed to be closer to the subject. As a result I was only able to make three dives with the 150mm.
Even in clear water using the 150 limits you to small subjects. However, using the +5 Sub See yeilds an good macro shot.(see feather star shrimp). However I did not think the shots were as crisp as with a 105.
I have not given up on the 150mm but so far I am unimpressed.