I've personally had some interesting experiences with metal bumper cases. I used to have a Galaxy S2, but now I have a Note 2 so I'm looking for a new metal/aluminium case. Check out my thread on metal bumper cases! My setup is similar to Ghost_1's setup; a metal bumper case with an extended Samsung 2000mAh Battery Kit and carbon fiber 3M Di-Noc on the back and home button. (Click the picture below)
I've been doing a bit of browsing around, and found this
very nice looking aluminium case for the Galaxy Note 2. There are a few things that I'm concerned about though - the battery cover and the headphone jack. In the pictures, it looks like the case will add a bit of thickness all around the phone, and the battery cover doesn't seem to be signal-friendly. As the Note 2 makes contact with the antenna built-in to the original battery cover, this case might decrease the signal by a significant amount.
The case I found didn't specify a brand, but from the pictures it looked like it is manufactured by "Zomgo", bringing me to this thread.
If I can't find a better one, I'm going to get another Sweet Armor.
They have one for the Note 2, but it's pretty expensive so I'm considering alternatives. My S2 one cost $72, but it was well worth it - no other case had a better fit than the Sweet Armor. <review mode> Made in Korea, the Sweet Armor gs2 has foam lining on the inside of the case, but it doesn't require much force to put the phone into it; the S2 can effortlessly slip into it like it was made by Samsung themselves. The external buttons are the perfect distance away from the phone's actual buttons, having a bit of elasticity holding them against the buttons. The added bulk is immediately apparent when you pick the phone up, but this directly translates into armour-like levels of protection. Due to the added ~ 5 mm thickness all around the phone, the USB port and headphone jack may become less accessible, but it was a sacrifice I was willing to take.</review mode>
Since I wanted to upgrade to a Note 2, I had to sell my S2, along with the case. I felt a bit empty after parting with such a legendary combination of battery and case...