I don't have any vignetting problems with my B+W 10-stop filters... No problems with the 82mm filter on my 24-70 or 16-35 lenses, or the 77mm filter with my 24-105 lens & a full frame 5d3... Now I do have big-time issues with the color cast of the B+W's! Color correcting the indego-blue of my Lee Big Stopper is a breeze compared to dealing with the peculiar orangey-magentaish brown tint of the B+W's, and they're not cheap filters! I may have to look into the Haida filters for when I don't want to hassle with the whole Lee filter kit...
@ Dustin
I would love to find a screw-in 10-stop ND filter who's color cast is easy to deal with! Those Haida filters of yours look very interesting... A quick Google of "Haida filters" found me this site where the reviewer does what appears to be a very careful & thorough comparison of the Haida filters with the B+W's: http://text.flowtographyberlin.de/neutral-density-filters-are-haida-nd-filters-as-good-as-bw/2/ Are your observations regarding the Haida filters similar to his? Particularly with regards to the color cast? His sample images comparing the color casts of the B+W's, the Haida Pro II MC (multi-coated), and the Haida non-coated are particularly interesting. In item #7 of the review, he points out that the color cast of the multi-coated Haida filters are quite similar to that of the B+W's. He appears to show that it is only the non-coated Haidas which exhibit a "slightly cool cast to it which is rather neutral and easy to fix." Has this been your experience also?
Lastly, where in the world do you buy the Haidas? A quick check with the usual suspects came up empty...
Agreed. It was due to the quirky color cast that I prefer Hoya over B+W, when it comes to circular ND filters. For everything else other than ND filters, I do in fact prefer B+W.
Here's a shameless plug of my search for the elusive Hoya ND X400
in 82mm a year ago ...
http://www.canonrumors.com/forum/index.php/topic,11564.msg206728.html#msg206728A year later, I've given up the quest for the above ND X400 filter. Alas I did eventually find some, but they were incredibly expensive (price gouging?); not worth it.
But wait, there's better news ... Hoya has just launched a whole new line of ND filters -- The PRO-ND series with
no color cast!?! (I would love to verify this myself)

Even better that it comes in
82mm (Hooray for 16-35 II & 24-70 II peeps!), up to
10 stops (previously 9 for ND X series), and
reasonably priced. It's win, win, win. The search is over folks!
http://www.hoyafilter.com/news/press/N0000026/B&H has them in stock btw.
