Just posting some typical guidelines.
For me, experiences rebuilding both coil over and air sprung dampers find both types will become contaminated with fine dust in the seals. More often the ones needing more frequent service live in a seal up environment.
Unsprung weight, is likely a moot concern with these large rod, mini dampers used on mtb applications. Larger dampers as used on motorcycles or performance vehicles can see a definite change. Can a rider feel the change, some better test riders will, but the average rider gets on and goes. Feel unsprung weight, many can't feel the end limits of a rebound adjuster.
As I said, just typical guidelines, nothing more.
PK