I'm doing 3 of the A360WE over my 200g which is 72x24x27. It worked out great this way since the tank is a DSA and has two braces, so each light has a 24" section to sit over. It's still a fairly new setup, so no long term outlooks, but I think the lighting will be fine for what I plan to do as a mixed tank but no SPS or super high light corals. So far my LPS including some at the sand level seems to like the lights running at 35% output and ramping up to 40% blue/white mix during mid-day. I doubt you'd have any problems with a couple of these in conjunction with your 150s. They put out more than you think they might for the size, especially if you kick them all the way up.
If you have a single brace you might be able to get away with two A360s a couple feet apart in the middle of the tank and then fill in on the outside with the 150s. But if you have two braces they are likely right about where you'd want put a pair of lights, so it may be the case where the braces are the deciding factor. Another way to save some money, if you aren't worried about the controllable A360, if you look around you can still find a few places with new (and under warrantee) A350s for < $300. At that price you can almost get 3 of the 350s for the price of 2 of the 360s.