All three spring units cost a little more for installation, and the cushions sit a little different compared to foam. Latex foam is the best filler, but its cost is higher than others-generally double the price. It is the norm to try to reglue open joints and reblock as permissible with larger upholstered pieces. It is impossible to open all the joints for full regluing, because of the seat and back spring construction. Seldom do the items have much of that type of problem.
Normal problems are loose arm joints or loose corner blocks which are both easily repaired.
Antique type upholstered furniture presents a very different problem. The repair and regluing of antique furniture requires a very skilled artisan and it is recommended his skill is approved by your upholster, if he is not able to do this repair work. Upholstery shops stock industrial touchup sprays and are capable of doing light refinishing on most furniture. However, it is not practical that they do the full refinishing of tables and the like because of the lack of proper equipment. Touching up the wood is a normal service for custom work.