Sounds like a clever way to catch the pieces. I don’t have the aluminum bars either, the plate is stiff enough.
I have never tried a puzzle, have looked…
That nasty mess on Jacks plate is the smoke condensing on it. IF the vent airflow is good enough both above and below the work it shouldn’t happen. Too high air assist velocity/pressure makes it worse as it blows the smoke straight down onto the cold steel plate and overcomes vent airflow. Your vent airflow sounds good, and of course it wont condense easily on cloth, just have to be careful you don’t set the cloth alight 
I managed to run a few pieces of Cut before I got the new nozzle and lens, D20mm, 2.5" FL.
The hardware cloth is the “Cat’s Meow” with one caveat, isn’t there always. The hardware cloth is difficult to make flat. I have done a work around concerning that. Will show some photos as soon as I get our taxes finished.
Of course it is, that is the idea. When you have hot gases, it will cool and material will condense out. If not in a single place it will be distributed throughout the whole ‘cooling’ pathway. Very little actually material actually stays in an air ‘suspension’.
Lasing causes expanding hot gas, both up and down. That ‘mess’ is what is caked in anyones honeycomb bed (or elsewhere) after a run. Honeycomb beds have no air flow in each of the ‘holes’. I thought they were the ‘sliced bread’ of tables, but my time with them has shown me otherwise.
I’ve found that my machine also doesn’t ‘stink’ like others do.
I want as much residue as possible left on the plate (one place) as I can. It wipes right off the plate. That is that much less going elsewhere in the machine I can’t get to for cleaning.
I couldn’t have enough airflow to stop top ‘smoke’ or bottom. It’s going to ‘smoke’ and you do the best you can to control where it goes. Ideally yes, in actuality is isn’t so easy.
Are the taxes holding the ‘hardware cloth’ down… lol
I use TurboTax and have for years. Also use Filemaker Pro for our database and ledgers.
Since we supposedly retired a couple years ago I don’t use either every day and that makes this old soul spend at least a day or more to reload my brain with what I have forgotten.
Gettin’ old is so much fun! Further complicated with the fact I actually do four separate accounts.
Wish I had a backup of mine. I think it’s corrupt memory… 
If you want that tar condensing where parts can fall Jack, fine. 
I don’t have a problem with them sticking. If it was an issue, I would not do it this way.
I use a brush to push them into a container…
It solidifies almost instantly. I can understand the concern.
It will solidify somewhere if not on the table all over the inside of the machine and the ventilation system. As it cools the stuff falls out…