The previous 800 and 600 were same diameter just different length is my understanding, so it seems this is something different. The latest video on the Atherton bike shows a very slim downtube too which I assume is the new 700.
I hope I'm proven wrong but a 600wh extender would be huge and heavy would it not? I'd be surprised if it could even fit. Would have thought a 300wh would be more in fitting.
Big difference in downtube size there.
Also interesting frame detail:
"Three Geometry Adjustment Systems (0.5°/1° Headset Cups, Chainstay Flip-Chip)"
I'd add for cheaper purchases you can definitely still do that, but for something as expensive as an ebike it makes a lot of sense to do your research.
If you're in the market for a Bosch equipped bike it's sounding like there could be some fire sales later in the year 🙃
(not a dig at Bosch's offering at all, just it's going to be a tough market)