I think as long as you don't accelerate really hard the chain will last just as long as it would under pedal power because it is under constant tension rather than high torque peaks from pedal pulses. I've run tiny #25h chain on my emotard that has 8 hp and like 16 lb ft at 200 rpm and it's only thrown a quick link once. Chains usually stretch quite a bit, but the failures are usually at the removable link I've found, or a binding link in the case of crappy chain. I chose the expensive Wippermann reluctantly, after looking at reviews and the actual design of the chain, it fits the most metal in between the cogs, and the link plates are flat, so they won't stretch out flat from tension like a SRAM or Shimano might.
The cool thing I like about having a derailleur setup with a dry lubed chain is that its really easy and clean to remove and inspect the chain, so I'm just gonna make it a regular checklist item. My other bikes with bigger chains covered with Tri-flow and dirt get less chain attention, but they're running 410H or 415H, which still stretches significantly but are less prone to bound links since they're just so big.
