We've got a bagless Bissel upright. Maybe our third bagless of various brands. I've dumped dirt from many vacuums, bag type and bagless. Seemed to recall the bags always puffing out dust when disconnecting them, or even from squeezing them on the way to the trash. Never remembered that problem with a bagless dirt container. Didn't know how to remove the container from the Bissell, so I asked my wife to dump it. About 2/3 full of typical house dust and dander/hair from our 2 dogs. She moved the lever, slid it out, carried it to the kitchen, put it in the kitchen trash can, and slowly turned it upside down. No dust left the trash can. Asked her if the dust will come out later and she said not unless she pushes something on it before she tosses other kitchen crap in there before she removes the trash bag. Says she won't. Anyway, we have no problem emptying the bagless. We like seeing what the vac has picked up and knowing it needs to be emptied.
The shop vac filter is a pain as others have mentioned. Instead of creating a cloud by banging it like I used to, I use a hose and water pressure, then hose the resulting mud down the driveway to the street or just into the grass. Depends which way I'm facing. Hardly any mud compared to breathing in a big cloud of crap. The price to pay is not using it until the filter has dried. Hasn't bothered me because I've taken to dumping it and cleaning the filter before it gets near full and when I don't need it. Learned my lesson. Keep meaning to get a second filter, but haven't.
--Vic