I have the Wynn filter on my Jet 1100 and I would defy anyone to proove it was a waste of money. Yes, i twas a 130 dollar upgrade for a 250 dollar DC, but the airflow easily doubled, if not more. The filtration level is MUCH better than the bags it came with. When comparing bags to canisters, look at surface area of the filter material. My cartridge is about 4 times the surface area as a single bag. That would mean i'd need 4 bags of a similar micron level to get comparable airflow.
The other problem with bags is they're rated to filter the fine dust AFTER they've already been pumping through quite a bit already. They have to build up a layer of fine dust on them before they really eliminate the 5 or 1 micron levels they claim. The specs on the bags tend to be a little marketing hooey, i've found.
Bill Pentz is considered an expert on this subject as he's invested quite a bit of his own energy/money/lungs into finding the best solution. His website (in regards to dust collection) is here:
http://billpentz.com/woodworking/cyclone/index.cfm
It's really a lot to read and can be a little bit alarmist for some. But i suppose i'd see his point of view better if i had to go through what he has.