Good points. You and your buds will have an easier time of it if your screen is a little under-filled (as opposed to over-filled).
Good point about the root mass too. I used to do pretty large scrog grows (one screen per light) and therefore had extended veg times - plants probably thought that they were outdoors lol - and large canopies. I grew them in those 20 ounce disposable Solo cups that I'd put so many ¼" holes in that they looked like net cups and then filled with the expanded balls for media. The cups were set in the lids of large plastic totes of at least nine gallons each with a DWC type setup so that the roots could grow unchecked into the reservoir. I remember that the roots ran rampant by harvest and cut the liquid capacity of each reservoir by half or so (and pretty much grew over/around/into all the airstones in each - but they were only my supplemental O2 source so was no big deal). It meant that by the latter stages of flowering that I was tending to the reservoir daily. A large fully-mature MJ plant transpires a LOT of moisture, especially when ambient temps occasionally hit triple-digits (I think had I been using any other system - one that did NOT supply constant super-oxygenated water to the roots 24/7 - that the heat would have been a show-stopper).
Oh, and the Solo cups ended up being disposable after all. Although I'd initially planned on reusing them (putting that many holes in each one was a pain unless I was in one of my OCD phases), it was not to be. The plant growing into the screen tended to over time force the cup even farther into the round holes I'd cut into each reservoir lid (sized so that the cup could only sit about half way into it). By the end they were barely sticking up out of the lid, deformed, and about half the time split/destroyed under the lid from the constant stress and the roots deciding that they'd rather be in the reservoir than in some stupid little cup (chortle). The Geolite/Hydroton is reusable, but when the roots have done a jailbreak on the cups and taken it with them into the reservoir, well... I usually lost half or so because I didn't feel like going on a scavenger hunt to pick them out of the roots in the reservoir.
Never had a problem with that method though - not one plant ever "fell out" of the screen. In fact, it got to be a running joke that I needed two helpers to help on harvest day (to hold each screen as I took them loose from the walls and then sawed through the trunk of the plant below it, and then to help carry each screen to the preliminary trim area).
Anyway, I ramble....
