Personally I think a refugium could benefit any saltwater system...all for the same reasons that they benefit a reef
1-increase water volume
2-remote location for equipment(heater/skimmer)
3-remote location for top-off..water changes..additives
4-predator free environment for fauna
5-site for macro algae growth that allows nutrient export
Over all a well set-up refugium can improve system balance and stabality...reef or fo........they simply work in my opinion.