If you don't adore the CX's dynamics, what do you appreciate about it? Perhaps the styling and early interiors? But surely what makes a real Citroen is the way it goes?
Regarding your questioning of the arb strength, that's a forum-filling bit of mathematics to prove things on paper - but I feel a massive difference between a Xantia and a CX on a road which isn't perfectly smooth. In a Xantia the obvious giveaway is the pronounced rock-roll which the neck has to deal with. In a CX, it just isn't there in the same pronounced way - in fact I've never noticed it in any CX or GS - or D, for that matter. The available roadholding and stability is subsequently of a higher and purer quality when the road springs and dampers don't have to deal with an unruly, undamped spring which both molests and unionises the otherwise independent front corners. Have a good look at the respective dimensions and engineering and you'll probably see what I mean.
Saab?
When it made its own cars (and was financially successful) arbs were absent from the large majority of its sales. One of the few manufacturers who really understood grip and roadholding.-for rallying? or road use? Who knows what's desirable without stating the aim. Is the aim success on a rally stage? Then Saab shows they are not desirable.
As for 'vibration absorption' not quite sure just what you mean, other than the obvious that at 20mph a car with metal roller bearings connecting the double-wishbone suspension with the driver - instead of rubber blocks everyewhere - is bound to transmit the road more accurately. But unmodded new spheres (see my other post), cheap tyres and minimum 27 year old body-to-chassis rubbers (and everything else!) is not going to make a CX feel good next to a Xantia designed to appeal to the roundabout-infested Mum-taxi...