I'm comfortable enough financially that I have zero worries about putting down $1100 with a 9 month wait when I can cancel later on regardless, but my feeling is that for most people they want to see a variety of reviews before they purchase. There's no real reason to buy yet without having some firm conclusions on how they sound and in that light the sales numbers look neither good nor bad but about what would be expected for a reasonably expensive headphone in this position with this wait time. When your target audience is mostly budget conscious audiophiles the currently low sales numbers don't really mean anything when that specific audience are the types of people to gravitate towards bang for buck products that are well-liked by the audiophile community. Currently there's no community consensus because no one has tried the product so you wouldn't expect high sales currently. Even if these were $1000 + $200 in points I don't see the situation being any different.
The Drop website has a 30 day timer for the current offer, personally I think they should hold the $1100 + 200 drop points for at least a week or so before reviews come out and extend this window if they have to. A lot of the criticisms are totally ridiculous but it doesn't make a lot of sense not to get this in the hands of reviewers. They could have easily waited an extra month before they were more comfortable in doing so then immediately had a variety of written and Youtube reviews ready to be shared. It doesn't seem like there can be a good justification against this, unless they were supremely confident in the prototypes.
On whether or not this is a failure again that completely relies on the quality of the end of product, which unfortunately no one is aware of yet. In terms of sales they'll easily sell thousands and thousands if the sound is well-liked by the community enough that it is even on-par with the 800s. Its 9 months out and no one has heard it, no its not a failure yet.