Jadis models last for many years - your JA-200 was introduced more than 20 years ago and the circuit dates from the 60's - I have the schematic of the original Loyez amplifier in a Millerioux application note from 1966. The type of capacitors changed during its life.
Using better electrolytic capacitors will surely improve the performance of your units, but the choice of signal capacitors are less obvious - they will sound different but it is very difficult to foresee what will be the effect in your system.
Some people I know and respect enjoy putting V-caps in Jadis and claim a much better performance, but I never compared them with standard units. Also, most high quality capacitors need 200-400 hours burn in time before they reach a stable sound, making decisions less clear.
How old are your units?