For landscape use, is there actually any meaningful difference from the 90 3.5 ?
Since we only recently received our 90 V rental/demo unit, I haven't had any opportunity to compare to the 90/3.2, since we don't have one of those. But - the 90/3.2 is a fine lens, in many cases, the new V lenses are not optically superior to previous XCD lenses, so for the same focal length, the main advantages are the new features built-in, such as Control Ring, Manual Focus Clutch, Distance Scale, etc.
If you have an existing 90/3.2, you're in pretty good shape, unless you really needed the slightly wider aperture, which sounds like you do not.
Many lenses can be similar stopped down to f/11, but there certainly are differences (otherwise, why make newer lenses?), whether this would be sharpness, either in the center, but more possibilities for differences usually reside at the edges, or even how OOF areas render.
Steve Hendrix/CI