With my aquscape and such, I have the 2 back Mp40's lower on the glass to blow the detritus from the backside of the aquascape. I love the MP40's, but I need the other 2 pumps to do the majority of the work load of various flow in the tank. I will use 2 MP60's only because I want a massive amount of flow and not have to run the pumps close to max. I really depends on the scape and what you will have in the tank. In my tank I have, roughly, a 4 in channel that runs the length of my tank, and it would be a pain to get a siphon tube back there. I think you plan is solid, it just depends on the scape.I just saw your post about switching your gyres over to MP60s at some point. Have you thought about doing 4 MP40s like this? I figured you could get some really great water motion this way, including a gyre effect, and not have to worry about detritus buildup in the back. This is my model of the tank on a 40" stand with 4 MP40s. Everything is scaled perfectly. Notice the child? This totally wasn't an attempt to persuade her.