is a slope down overflow pipe quieter than straight down?

[viodea]

I'm putting up my 120gal tank. It's time to do some plumbing. I'm going to use a durso overflow.

I have dual overflow and 3 compartment sump. I can either have my overflow goes straight down to the left (skimmer) and right (fuge) side of my sump or have them crossed from left side of the tank to the right side of the sump and vice-versa.

Does it worth the effort to do it?
I'll have a 90 elbow at the end to a drilled pvc to slow down water flow. Should I submerge the pipe or have it half way seating on the waterline?

thanks