Performance wise, there aren't any real changes between the homebrew setup and the Gorilla intake, as they both draw cold air directly from the hood scoop. Both systems use a K&N Filter (I just purchased a new one to replace the beat-up one that the RS came with) and they're both hooked up directly to the intake manifold on this MAP-based system. Really, the only thing that was wrong with the homebrew setup was that I wanted something a little more solid that could take the same abuse the rest of the car has managed to endure so far.
Derek's intake is actually crash tested, as he recently had one out of a wrecked RS for sale that only had scratches on it. It's built with a durable 6061 aluminum box that uses factory mounting brackets and is finished with a heat insulating black powder coat application. As with the weather applications, I can say that I have put the homebrew system through it's paces. The Gorilla Intake was mounted just before Winter Storm Dion and I drove the car all day through it with no issues. Even after I had the car parked for several hours and snow had accumulated onto the hood. I just started it up and drove away with snow flying off the car. I'd imagine snow ahead of the hood scoop made it's way in, but after inspecting the intake once I was home, there still were no signs of any water that might have melted through.
I'd say that, for normal driving conditions, the homebrew system does just fine. It wobbles a little and I'd just worry about the intake getting tossed around. It also took me a couple tries to get the fitment right and I was never 100% happy with how it sat under the hood scoop. With the Gorilla intake, fitment was spot-on. It's rugged, sturdy, and I just feel more confident with a solid setup like this whereas with the homebrew system, I was checking under the hood every time I hit a bump to see if it had wiggled itself loose or something. I can focus less on worry about the car and more on bettering myself as a driver.