@Calson
Have you tried the Z400TC yourself for any length of time?
The hand hold ability of this lens w/access to the Lens Fn buttons & rings is really quite subjective, and I'm in the Brad Hill camp and found for my hand holding style I had good access to the mentioned buttons. Looking through the various reviews I found that it was only Thom Hogan who did not like the handling/hold ability w/button access.
Just to clarify, I've been shooting with long prime Nikkor's for over 35 yrs.
I was fortunate to shoot this lens on a Z9 in March in the Serengeti (granted for only a day) and loved how it felt and balanced in my hand, so much nicer than my 400E, now since sold.
My 400TC is arriving from Nikon in just 2/3 days, and can't wait!
I'm really looking forward to putting this lens through its paces on my upcoming month long Serengeti assignment in 2 weeks.