Hey RR,
i did heaps and heaps of research when we were getting our shop setup with a proper dust collector.
looking at all the stats, the bag and/or drum type filters just did not cut it.
the filter bags let the fine dust escape, they were purported to have incredible cfm movement( tested in labs etc!), until actually put on a real system, and not one worked well.
Extensive Research revealed a guy called Bill Pentz, who put excessive amounts of time into researching and designing cyclonic extractor's.
he sold/ gave the manufacturing rights for his designs to a company called Clear Vue. We ended up purchasing their biggest unit, and it has proven to be one of the best investments we ever made.
on Bills website, he offers free plans and kits and parts for his units,
but we just bought from Clear Vue.
no more dust, the drum catches everything, and they have a full range of sizes. from a dust deputy size right up to a 5hp unit.