Yes but I believe a little more so in taller aquariums, giving you a larger range of par at certain levels. That was your not cooking your lps with sps light.
My thought and it's a pretty simple one is that if your keeping SPS than you can keep everything else LPS leathers shrooms zoas anemones etc. the only category of coral that needs special attention is your azooxanthellate corals. LPS in my opinion can and usually rely on small particles and nutrients out of from the water column, and of course photosynthesis. SPS will rely more on its symbiotic relations with zooxanthellate but will also supplement from nutrients in the water column.
I sure hope so.... that's my game plan and the reason I'm upgrading from a 125 to a 180. Would have liked an even larger tank but don't have the room for it.
You definitely can. I have about 25 different SPS, 15 LPS, and 15 different softies in the same tank. I feel like I am always making slight adjustments especially when I make new additions but that's part of the fun. Just arrange your rockwork so you have areas of high flow and low flow and also have places with high direct light and slightly more shaded areas. Of coarse the taller your tank, the easier it is to create those different environments. You also have to watch out for sweeper tentacles from those LPS as they can damage SPS extremely fast.