Deeply discount the idiots over there!
I started doing the retort bags quite some time ago, before AK Butcher Supply really got the hang of it. I lucked into the right set-up because my pressure canner uses a gauge and pop-off rather than a rattle to maintain pressure.
The rattles leak too fast during cooling. This venting causes the bags to swell as the contents are still very hot and the canner pressure drops significantly.
The pop-off style maintains the air/steam in the canner far longer and by the time the pressure/temperature drops in the canner the bag contents are cool enough to not swell the bags. I have not lost more than a few bags out of hundreds. I have seen loads completely fail in the rattle-style canners.
As to your space concerns, you are correct, the vac packers are bulky, very heavy, expensive, and the bags are not cheap. But glass jars take up more space by far...
I still do some jars as they are still hanging around and do okay on small batches. Retort bags can be packed tightly in the cooker and you pack more product per canner load, by far, that way. That is a huge time saver when packing moose and caribou.
A couple years ago I did a huge batch of chili verde and the bags made it much faster and easier. It was six average black bears at one time...