BM Skimmer Ratings

[intarsiabox]

I'm looking at adding a sump to a 40g breeder so I can get some more real estate being taken up by a Tunze 9004 skimmer and heater. The two skimmers I'm looking at are the BM Curve A5 DC and Curve A8 DC. The skimmer may also end up being used on a custom 75g as well in the near future. Currently no fish in the tank just mixed corals and shrimp but I would only stock a few smaller type of fishes like wrasses, dartfish, etc. so bioload wouldn't be really high in either tank. The A5 says it's rated for 50-150g and the A8 is 180-235g which seems excessive for what I need but I don't know how or if BM's ratings are highly optimistic. Any thoughts from BM owners?