I collected info on 'giraffe' tanks (tanks with sensors or even weapons or a manned observation platform on a long elevatable mast) for some time. The intent was to write about them, but that story hasn't much flesh.
It's rather simple;
(a) It's stupid to use a manned mast because of today's technology.
(b) It's apparently unnecessary to mount weapons that high (lasers and guided missile launchers were included in some projects).
(c) It's quite common to use such masts for sensors and/or long range radios.
The most interesting vehicle of this kind is in my opinion the Czech artillery observer vehicle "Snezka" (that's a mountain).
A 14 metre mast with battlefield observation radar, laser rangefinder, day/night TV, thermal sensor (likely bsolete by now), wind sensor and a good radio offer almost everything that artillery observers could hope for (in such a vehicle). It certainly embarrasses the by comparison limited CV90 FOV.
I think the Czechs deserve a bit more attention with such an impressive vehicle concept.