Gear VR is garbage even compared to the DK2
Disagree. Since getting a Gear VR I've barely touched my DK2. Losing positional tracking and 75hz is a shame, but the displays are much better overall with SDE notably reduced, and the software experience (Oculus Home) is much better. Head tracking is that bit tighter too (just talking rotational as again, no positional) and the headset is a good deal lighter. Plus I really like not being tethered... which is partly why I'm planning on putting my camera *behind* my PC so that the cable is behind me back to the PC when I turn around to face it.
I have found it much more comfortable to wear for extended periods of time as a result. I am very happy to hear SDE is greatly improved in the final Rift, and that it's much lighter than the DK2. 90hz will further improve motion to photon latency (although I think part of why Gear VR feels better there is due to time warp, and I know that wasn't fully integrated into the 0.8 SDK, which is I think the last one Oculus publically released).
To address the worries... yes, the sweet spot should be better. The 'blur' on my Gear VR isn't too bad... make sure you're adjusting the dial on top of the unit. Not every game on Gear VR adjusts for the chromatic aberration of the lenses which every game on the final Rift will. And while the Rift likely has slightly reduced pixel density, with the lenses on the final version (and from what I've heard, the Vive has some optics to help with reducing SDE too) SDE is greatly minimized.
As ever with VR, until you have the headset on your head and you're trying an experience it's very hard to gauge how readily apparent such things will be.
The retail headsets will be better than the Gear VR though, I don't doubt. But I'm sure you'd think the DK2 was garbage also, if you felt that way about the Gear VR.