You are making some confusion here: The F90X doesn't need some Shift button. In Manual the Command Dial operates the shutter speeds and the Aperture is operated by the aperture ring on the lens.I have always chosen the f/n 80 over the n90/s.
I am ALWAYS in manual mode, and I find it inconvenient to only have one wheel, so that I have to do some shift-button to change time or aperture.
That's why G lenses, who don't have an aperture ring, don't work in A or Manual mode on the F90.
Apart from what was said before, I'm sure my 4 F90X will survive me. It has a core of metal, so it is a bit heavier and sturdier than the F80.
I'm not sure why the F801 does that, but the SB-28 was made for the F5 and F90. I use the older SB-26 and it is perfectly compatible with my F90X. In fact, it was made for them! And yes, the zoom head on the flash does work with my F801.Talking of which if I use a separate flash on the F801, with a SB28 it will remain on the widest setting, whilst the F80 will zoom in and out as the focal length is changed.
Could you check the manual for the SB-28 and its compatibility with the F-801? If they are compatible on that aspect, then I suggest that you look at the F-801 flash contacts. They might need some cleaning. Good luck!
P.S. If you don't have the manual, here it is: http://www.nikonusa.com/pdf/manuals/...ghts/SB-28.pdf
I had a look at it and the SB28 should be compatible with the F-801, even the auto zoom should work. Check your F-801 flash contacts. That happened to me once with a F90.