I've had some trouble with where the Wynn meets up with the DC barrel. The hf collectors aren't exactly known for being precision instruments and mine at least had some warping there. I've mostly solved that part by putting another couple rounds of gasket on the bottom of the filter. Getting the filter to seat right with the provided turnbuckles was a bit fussy as well, so instead I tied four chunks of bicycle inner tube together with hooks on the ends and just stretch those over the top of the filter and hook them onto the DC body which allows it to kind of settle in place on its own terms. It also makes removing the filter to clean it out fairly trivial.
The one I have also had a bunch of smaller leaks here and there. Usually you can spot them by a small spray of dust coming out of a junction or screw hole. I've since liberally applied duct sealant (mastic from the HVAC section of your local big box) to most of the junctions and that slowed it down a lot. You want to vacuum and wipe up the dust good before applying the sealant so it sticks good and give it plenty of time to cure so you don't blow it back out (overnight works as long as it's not applied to thick so it's a good end of day task, look for leaks then seal them up).
The other points about the DC not collecting everything are pretty true as well. Some table saw and router operations just spray dust despite the collection, better guards with improved collection points would surely help some. A stronger DC would also definitely pull more in, for a couple of my machines the hf barely keeps up with chip collection nevermind the fines.
If you sweep up real good and wipe everything down you can get a pretty good idea where the dust is coming from by doing a bit of inspection after doing a quick run, that is generate enough dust to see what's going on, but not so much that it obscures the sources.
You shouldn't have to tape the house though, the hose clamps should be enough (at least in my experience..).
