OK so I'm holding off on the full review until I receive the sportback/composite back in a couple of weeks, but here's my user experience with the aluminum back diamondback.
First and foremost, this thing is a formidible case. It's heavy in the hand and gives the phone a very solid feel, more reminiscent of the phones of old - you don't have that "holy crap this thing is delicate" feeling that you get when using a naked iphone 4...and it's sturdiness has been proven in my own accidental drop test:
When getting up from my desk, my chair arm caught in the charging cable for my iphone. This caused the phone to be flung quite hard against the air conditioner in my office. Thankfully it hit back first - phone survived without a scratch, as did the case. In terms of protection, therefor, I would give this thing 5 stars - it doesn't protect the front ala otterbox, but what it does cover is VERY well covered. The aluminum used is clearly pretty hardcore!
On to the other stuff: early on I noticed a definite drop in signal strength: about 1 bar from both wifi and 3G service. I consider that to be an annoyance more than anything else, keeping in mind that this IS a full aluminum back: a bit of drop is to be expected. I wasn't seeing an increase in dropped calls or any real data issues. However, where the phone really struggled was in GPS: I rely heavily on my phone's GPS to be accurate at all times...and unfortunately with the DB on, it very clearly had a hard time locking onto me. While it would always eventually pinpoint within a block or two, I would often drive for as much as a mile or two without the famous blue dot moving at all - meaning that while I essentially knew where I was, the GPS was not going to be much help in knowing when my turn was coming up. The effect was bad enough that I stopped at a CVS and bought an eyeglass screwdriver to take the case off (at which point GPS was fine, and I also confirmed ZERO damage to the back, despite having taken as hard a hit as I've ever seen).
The side wobble reported by some others is present, but also to be expected as it is the bit where the composite piece is cut to give access to the volume buttons and the like - nothing unexpected or objectionable from what I could tell.
Overall, I love the case. It looks great, feels great in the hand, and is clearly better protected then using any of the frame or bumper styled cases. It adds a fairly substantial amount of heft to the phone - I find this to be desirable actually - and definitely does have some impact on signal/gps. I informed Atomic about this and received the following response:
"ITs an all aluminum backplate.. We have tested in in various parts of the country and couple of countries in south east Asia without issues.. In Chicago, West Palm, and Kansas and GA there are some issues with GPS and signal dropping 1 to 2 bars sometimes.
However, what we decided to do is (in production now) create an identical backplate in composite and include that with every DB sold called the "sport cover" for those who rely daily on gps, signal, etc..
We (when this sport cover is completed in 10 to 15 days) are reintroducing the DB in plated chrome or plated satin* (Composite) which will additionally come with a black sport cover (also composite) , all for 100.00
For 100.00 more the aluminum junkies can buy the metal backplate.
We thought this through and we really do not want our product to circulate like the (redacted competing case name) killing signal but looking good."
* composite is being electroplated in chrome and satin chrome (you can not tell its not metal) and finish is superb"
Overall, I love the case - it has a really cool look and a great feel. Be aware that, as with ANY aluminum case, you will see some impact on your signal with the aluminum back. I'll definitely report more once I receive the composite/sportback. The response above does also show, once again, that Atomic is also committed to its customers and putting out the best possible product. While I've gone back to my hybrid for the moment, the diamondback will certainly stay in my drawer and be pulled back out when the alternate material backing is available!