@Shrike -- We make the SRAM RED DZero and Quarq DZero Carbon power meters in 165mm. Sometimes they are harder to find because 170mm, 172.5mm and 175mm are more popular and therefore more often stocked by resellers. I would recommend you talk to a dealer, like you have, or use SRAM's distributor and dealer locator that I mentioned above.
@moonoi -- The previous generation power meters do not have inherent problems that have not already been solved, such as improvements made to the battery compartment over time. Every power meter that left the factory passed our IPX7 underwater test. The DZero platform is a better all around power meter because Quarq has now made power meters for 10 years and everything we've learnt is in that power meter platform. It has improved measurement, new features such as Bluetooth, and also things we believe make it even more durable.
@michaelten -- The DZero power meter spiders only fit cranks with the 8-bolt interface. You can see the list of compatible cranks on the Quarq website (click Specifications). https://www.quarq.com/store/item/1772/
The 8-bolt interface secures the power meter spider differently than SRAM's traditional 3-bolt interface. Instead of having the spider mesh with the crank arm, the spider is secured with T20 Torx bolts just like a car wheel is centered and secured with its lug nuts/bolts. Doing this promotes accuracy when someone installs a power meter spider outside the factory. When power meter spiders with the 3-bolt interface were installed outside the factory they didn't see huge changes in accuracy, but we advertise +/-1.5% accuracy and wanted to keep that promise. Particularly for the new Quarq Prime Power Ready Cranksets.
The DZero power meter spiders have been made since late August '16 and are available worldwide, in 130 BCD and 110 BCD.