As you mention there was quite a long discussion on these a while back. It has possibly fallen off the Forum with age, something that is going to be addressed in the future????
The fitting of the shock adsorbers will undoubtedly limit the movemet of the suspension and many people have noticed a difference. However, it must be said that many vans are supplied without them and even ALKO do not see any specific requirement to fit them to all their products. Any damage such as cracking would I feel be difficult to associate with just the lack of a shock adsorber. That would be more of a case of poorly fitted panels, or even substandard panels.
After sales fitting is entirely up to the owner. I have had vans both fitted, and not and never really noticed that much of a difference. I feel that good loading practice will eliminate many of the problems that can be possibly thrown at shocker absense. As they are not a high price item then why not, but do not use that as an excuse to load excessively.