Thanks for the help guys. I will take a look at the Lagunas, how quiet are they? I didn't put much consideration into watt usage until now, I will look into this some more. I was originally going to use only the wet/dry filter though I've been reading that mechanical filtration on them is weak. Maybe I'll run the wet/dry first and if needed I'll add the fx5 later, luckily I already have it, lol. So it would seem that I'm better off using only 1 return pump for both overflows vs 2? I'm not sure if any head pressure is added running only one pump for 2 megaflows?
Glad to help...I like talking about pumps and filtration.
In regards to your lower electric bill, I did the math; assuming you pay the national average for electricity of $0.11 per KWHr, you would save ~$66 per year by going with the Max Flo 2000 over the Mag Drive 18.
I'm running the largest Laguna pump and it is very quiet. Noise level, efficiency and reliability were my main concerns when I was looking into which pump to use. In the research I did and now in my own personal experience over the past 2 years, Lagunas rate really well in these categories.
In regards to running 2 pumps, you could go with 2 Max flo 1350s. They do 679GPH @ 6' head on 75 watts each.
There would be no added head by using two pumps and the redundancy of running two pumps is nice- you would just have to decide if it's worth the extra initial cost to purchase both pumps and the added electricity cost of running two pumps.
I'm not sure you really need the FX5, but other than the additional cost to run it (about $50 per year using the same assumptions as before), it wouldn't hurt.
BTW, I used 6' of head in all my examples because even though you said you only have a 5' rise from your sump to the top of your tank, friction loss from the plumbing will add at least 1' of head.
Good luck!