I have not seen a copper base on a heatsink since my Freezer Pro 7. That had a 92mm fan, which made it too loud at 2000-2500 rpm, but even with three narrow heatpipes, it did cool.
Keep the copper base.
My experience with an NH-D14 tells me that having air blow out the side and get sucked into the sides improves performance. When I close up the sides the cooling performance got worse. So I like that offset fan design: keeps it low and wide while using the whole width of the heatsink. You end up with more surface area, and more blown surface area, than you would with a straight non-offset design.
Keep the offset, but do a good job at educating consumers.
I have a Hyper . . . a Hyper Z600R. I bought it from the CM refurb store, and even bought an LGA 1156-comptible mount for it. Maybe it wasn't the best heatsink I could have gotten, but it went into a non-OC'd rig and it sure was fun. I removed the Sickle Flow it came with and used a San Ace Silent, a 9S1212L401 (BTW -- including clips for two fans was very considerate).
But I will not be using that heatsink again because the mount -- both mounts -- were such a pain. If your N520 uses the same mount, you will end up either with no positive word-of-mouth, or -- because these days we have excellent mounts on heatsinks -- negative publicity.
Design and sell a new mount.
BTW -- if you sold a good new mount that is backwards compatible with old heatsinks, I would get one. I really enjoyed that Z600R.
As I thought about it, you could do an offset heatsink with 120mm fans. You might get just as good a cooling performance as with a 140mm heatsink. After all, the top of the finstack with a 140mm fan hardly gets any wind across most of the plates.
Edited by ehume - 10/30/13 at 7:14pm