Brian you have a 2016 DSR right? That has a 28/130 gear and a top speed of 98 mph with 90 mph sustained. The SR has a gearing of 30/130 and so a top speed of 102 and 95 mph sustained.
And Burton I'm fairly certain your motor bearing failure was due to aftermarket ceramic bearings that might offer less friction due to amazing smoothness and hardness for racing but aren't as durable long term. I had a 28/98 setup and my newer 2013 design motor (on my 2012 Zero) has gone tens of thousands of miles and runs like it is brand new.
The DSR tire is 130/80/17, which is about 2% taller than the 140/70/17 on the SR. This will slightly reduce the gearing advantage from the 28 tooth front.
With the tire difference, the DSR is geared about 5% higher than the SR and should accelerate to 60 a bit faster. Yet Zero claims 3.9s for the DSR, where they claim 3.3s still for the SR.
Off-topic alert:
In various third-party instrumented reviews, the SR has tested as significantly slower (with an American-sized rider) than Zero's claims. I wonder if the DSR's performance claims are closer to the actual performance, and Zero simply can't/won't adjust the SR spec to a more accurate number (to avoid negative press over "lower" performance).
Has anyone run a DSR against a SR to see which accelerates harder? I've ridden a SR alongside a DSR but I didn't think to do a full acceleration test.