It is apparently tough to get a good SPS/LPS/Softie combo tank.  
The SPS of course want the purest of water, and lots of flow.  The others like a bit more nutrient in their water I think, and some like a lower current.
Then there is light.  A lot of softies won't thrive in a highly lit SPS tank.
That said, my tank was a softie LPS tank and I really liked it.  I'm kind of regretting trying to make it something else.  It's also going through a change now that I have removed so many of the LPS, more algae and a phosphate reading I've never had in four years.  I don't know if that is why.
But I'm glad for your post, because now something I have been struggling with is clear to me.    I don't want SPS in my 155g.  It was fine the way it was......
Okay guys bring my corals back..... 
  
  