Well it depends what you want to use the pump for. I don't believe in using return pumps for circulation as I think it's a waste. Unlike circulation pumps, return pumps have the disadvantage of being located not only outside the tank but a few feet below it. My return pump uses so much extra juice just getting the water up four feet and over the top of the tank. For example, my
vortech pump (used for circulation) moves 3,000 GPH at 14 watts. My Ehiem 1262 (return pump) uses 85 watts to move just 900 GPH! I'm much better off using my vortech to produce all the flow that my reef needs and using my Eheim pump just to produce enough flow to feed my skimmer and my refugium.
That being said, the 90 degree elbows on my return don't cut back all that much head loss. According to the head loss calcul
ator on RC I'm losing 19 GPH by having two 90 degree elbows. Since my pump pushes 900 GPH and I keep it throttled back to only 50% because I don't need any more flow, the extra 19 GPH don't matter to me. My skimmer needs only 133 GPH and my fuge gets about 100 GPH which is honestly probably too much. My fuge is only 20" by 12" and maybe 6 inches high so 100GPH passing through there is a considerable amount of flow. Pushing any more than 250GPH though my return pump (after head loss) wouldn't be doing me any good. That's what I love about circulations pumps, be they powerheads, tunzes or vortechs.
As to the 90 on the intake, quite the contrary its a great idea (thank to Badcofee on that one.) The 90 on the intake doesn't cut the flow at all (and if so it's negligible) as the pump is internal, if it was external it might be different. Also the benefit of having a downward facing intake is that I can open my pump to 100% if I want and push 800GPH through a 15 gallon sump with only one baffle and not get any microbubbles! It's fantastic and only costs about $.79!