Good Vehicle
I'm also 6'4", but with a lot of that height in the body. ...also owned a 4Runner a while back (1990). The CX-9 needs more headroom, but that's a fact of life among every Japanese vehicle I have ever owned (Toyota, Honda, Lexus, Acura, now Mazda) I also don't like the seams in the seat bottoms and think the seats in general should be deeper/longer for us big Americans.
My major complaints after 2000+ miles are that the paint is thin/weak and the acceleration could be smoother out of 1st. Side door moldings are available aftermarket, and I may put them on myself after seeing the susceptability of the paint to nicks. No other maintenance issues so far.
FWIW, I came out of a BMW 740il into this vehicle, and of course, there's no comparison in ride and handling with a sport sedan. The reliability of the autobahn cruiser was piss poor (fantastic paint though), so it will be hard for the CX-9 to let me down.
Given the other choices in this segment, the CX-9 is tough to beat.