Oddly...the "standard" drawings he has use 1" for "drain" and 1.5" for the rest of it.
It's definitely based on the durso. The only difference between the main siphon and a typical durso is that it's meant to be a full siphon at all times, which should make it dead silent.
The second line is a true durso, but the amount of water flowing through it should be very minimal, which should result in it being silent as well. The more water you have going through it the more noise it's going to make.
The third line...yeah, probably overkill. It's for the "failsafe" claim which, if you have enough room in your tank to hold the volume of water that you can pump out of your sump, you should, technically, never need. (I know you harp on this one Mike. )
I have a regular durso standpipe in my 75g right now. It's not completely silent, but it's not terribly noisy. The main thing I don't like is that I've never managed to get the return pump and the drain completely matched. About once a day it flushes. More often if I don't keep the hole on top cleaned out.
If I was 100% sure I will never want to do a wave I'd definitely be going with this setup. It's not that difficult to setup on a new tank and should be pretty much dead silent, setup correctly.
But...with the thoughts about a wave I may end up with something different.