Those overflows styles work well. They all work on the same premise in that water enters the pipe from a point under the surface, thereby eliminating the toilet flushing sound as water gets sucked into pipe. And you have an air input solution because you need air going into the pipe as well.
If built correctly they won't really be prone to clogging, I mean any kind of pipe can clog obviously but do things like put teeth on the overflow, or a strainer (if you go with a Durso), and things won't be able to get in there.
If you're ever in the deep south end of the city, you're welcome to look at my tanks, I have some Durso's going and a Stockman/Hofer derivative, if you're just in need of seeing something in action.
As for pumps .. I think you will be disappointed with the noise level of the Mag drive. They are great pumps, I love them, they are workhorses that just go and go and go for years on end, and they're not too expensive ... but they do rattle.
The Eheims are supposed to be one of the best pumps out there. But you do pay for the premium. I haven't tried one myself yet but I hear only good things about them.
Another option to consider is a Sedra .. I have one on my 65g planted tank and it was the second pump I tried for that tank (first one was a Mag5 and it just made the whole tank and stand howl .. it had just the right resonance). I then tried a Sedra 7000 but it was too much flow - I finally settled on a Sedra 5000 and it's a perfect fit. One, the pump size is physically smaller so it fit in my sump better, and two, the flow was right, and three, although not whisper silent, the noise level was much more within tolerance (this is a tank near bedrooms so it was imperative to be quieter). The Sedra model #'s more or less correspond to the Mag drives. Ie. Sedra 5000, Mag 500; Sedra 7000 Mag 700, etc. etc.
There were other pumps I considered as well, but I don't remember all the names.
The Hydor Seltzer pumps are really nice and quiet but I don't think they come in a size big enough for what you want.
I wouldn't push more than 7 times volume through the sump. Any more and you risk microbubbles in the main tank. I suggest aiming for 5-7 times, and then makeup the additional tank flow with powerheads, closed loops, wavebox, Tunzes or Hydors ... you'll be much happier with the end result.
