B&H is honest about it. The problem I have with Amazon is that they aren't. Based on price and representation, the lens I bought was indistinguishable from a US-market unit right up until I took it out of the box and checked the serial number.
To be clear, I suspect error and not malfeasance on Amazon's part. But I don't really care which it is, either.
Yup - B&H gives you the choice of whether you want to trade off price for potential issues down the road.
With Amazon you may get zonked and have no way of knowing until after the fact. And seeing the other comments about Newegg, that's disappointing too. Luckily I live near more than a few Microcenters - but finding reliable, trustworthy electronics retailers is becoming harder and harder.
That's honestly most of the reason I still go to the store, and all of why I'll go out of my way to buy there even for stuff I could probably get elsewhere for a little less.
Micro Center is the last of the old breed of computer stores, where you could expect to go and find a strong product selection and generally knowledgeable people - I can't remember the last time I've gone anywhere else and found the sales staff able to usefully consult and advise on complex questions; by contrast, I've learned through experience that I can go into my local Micro Center with nothing but a problem description and come out with a solution that will work.
I want that to go on being the case for a long time; after all, I'm not getting any younger nor are days getting any longer, and having kids around who are, by all I can tell, well paid and fairly treated precisely to develop and apply knowledge I don't have the time or honestly the desire to obtain for myself - that's something I'm not just willing, but happy, to support.
To be clear, I suspect error and not malfeasance on Amazon's part. But I don't really care which it is, either.