Disclaimer;
I am just a photography for fun guy who has used many a camera on an off throughout my life. Very much a "hard scientist" who understands a lot, but not all advanced math. Not an engineer, but have worked closely with various flavors throughout life. Understand the mindset and many basic engineering principles, but there are folks here (Erik amongst them) that have likely forgotten more than i know.
FWIW I own both those lenses and love them on my lowly 6D
But I can read too, and am perfectly capable of drawing conclusions of some validity... so;
Have read page after page of complaints, both large and small about non-compatabilities between lenses and bodies with use of adapters. This makes basic sense to me. You take camera "A" and lens "B" whose design goals and parameters were never optimized for each other and expect a CNC bit of metal to bridge that gap. As if something as complex as steering photons is a simple matter to do at the degrees of accuracy that many of us demand. In fact, my intuition is that folks should be happy that it works at all, not that it does not work always. Sometimes it's not just the ray tracings, but the secondary systems (shutter functions) that mess things up and again, no engineer should be at all surprised. They know that things typically have ideal operating ranges that if exceeded can yield undesirable results.
With apologies to many, this is precisely why Sony holds no interest for me (except my lovely RX-1). Though some of the folks here love them and they indeed understand the complexities.
If you're talking about getting a D800 and big Zeiss glass for particular use you are not a poor man and I would say, have at it. My objection to Nikon involves skin tones and the lenses you speak of are hardly portraiture glass, so go for it. I would guess you want to crop your WA shots and the 800 with twice as many pixels is a logical choice for such approaches.
Just one guy's opinion of course, but look around yourself... places like B&H are great for this since their return policy is bulletproof as long as you play by the rules and you can try before you buy.
75M...
Gonna need a lot of fancy subsystems to keep those images sharp, but I am thrilled. Can I put in my order?