If I were Zero I would make darn sure they get out before the Brammo Empulse arrives at dealers. Apparently, that is beginning now, but only a trickle. Lots of stories of people waiting for an Empulse, but buying a Zero because of the long wait. It may just work the other way around too, at least for some Zero models like the S.
I think that any "trying to get their foot in the door while Empulses are still scarce" ship has already sailed at this point. Both are hand assembled and so both will be scarce while the initial supply fills the preorders. All of the Brammo dealers should have had their Empulse demonstrators by the middle to end of December. I am one of the highest Empulse reservation numbers in the system (that put an actual deposit down) and I should be seeing a delivery by the time that demonstrator Zeros arrive at dealers (note that that doesn't mean all ~2000 preorders will have been filled as only a fraction put down deposits, only the serious depositors will have been filled by then). By all accounts, the supply of Empulse bikes should be equal or better to the supply of 2013 Zeros at any point in time moving forward. Brammo probably had a better marketing engine leading into the deliveries which will likely translate into more deposit-paid preorders, but once bikes are available on demand I don't think Zero will be ahead of Brammo in terms of supply at any time. (Unless anyone has any insight into factory throughput for the two makers?)
One caveat to the preorders being filled is that the Brammo dealer network is scarce and so some people in parts of the country with no nearby Brammo dealer may have had trouble getting their deposits filled with a bike and may switch to Zero if the Zero has better delivery options. From what I've heard on this forum, Zero may be moving more towards a dealer model and so, with both companies shunning direct deliveries, the size of the dealer network may be a larger factor than the timing of the release schedules.
But, I agree that a race is on here and sooner would be better than later for the 2013 Zeros.
Also, has anyone actually "bought" a Zero because of giving up on an Empulse since the deliveries got real back in early December? I would think that many failed to place deposits on the Empulse while waiting for more direct info about the 2013 Zeros, but "buying a Zero" because of the wait would have been something that would have happened this summer and early fall when the choices were a 2012 Zero vs. an unknown delivery on the Empulse. Now that the Empulse is "real" I don't think any serious customers for a bike like the Empulse would give up the wait to buy a bike with the 2012 Zero specs. I do think a lot of people on the free preorder list failed to convert to depositors when they saw the 2013 Zero announcement, but they couldn't have "bought" yet - they will stay on the fence until both are available for test rides or reviews, which won't be affected much by the small shifts in timing of getting the 2013 line out.
At this point, with the Empulse actually shipping and nearly filling the preorder list, I think most of the decisions have been made (buy an Empulse, stay on the fence, or definitely buy a 2013 Zero when they are out) and unless Zero sees a shipping delay on the order of "months", few people are going to change between those camps at this point. (Though, depending on the issues around lack of Brammo dealers, such shifting may occur in markets with no reasonably close Brammo dealers. Brammo is actively working on that network, though).