I have only ever owned used equipment, both photgraphic and optical, and have never had a warranty other than homeowner's insurance. I buy quality stuff and have rarely had problems, and on the occasion I have I was able to get service through the manufacturer for what I considered a reasonable price.
Grey market binoculars, the high end stuff at least, cost from 30% to 50% less than new.
Would you, given the already high workmanship, consider giving up the warranty and in doing so saving many hundreds of dollars?
When I researched this a couple of years ago, I did not consider the savings I found on-line for gray-market Leica and Swarovski (this was before the Zeiss FL) to be sufficient to give up the warranty. And I did not find savings of 30% to 50%. Maybe that's the savings from the importer's list price, but not from what places like Eagle Optics were charging. Even the best products may require service, and I'd be pretty ticked if I had to send it back to Germany, probably not to be back in my hands for many weeks. But that's just me.