I actually like them Chuck. They are flexible but the part that hits an obstruction will be pushed in rather than the whole filter bending. It will of course rub and wear. No problem, just seal up with some tough goop like sika flex.
No light shines through them and you use normal products. Turpentine to clean and a 50/50 turps/engine oil to oil.
I do find that as they are actually a filter rather than a gauze/cotton seive they are just slightly more restrictive but nowhere near as much as the trendy little cone shaped seives due to their larger surface area.
I can always find a position of rotation for them to sit freely. I have them on the monza, V65GT but they are of course PHBH carbs so a bit smaller. I have the big ones on a Cali III without issue too.
I've used both the straight/steel cap abnd the angled. The angled give much more surface area but I have put holes in the steel caps to plumb the breather system into.