On OG Crafty and Mighty the entire bowl is aluminum. This has been revised to ceramic coating on (I think both) +'s. Now some folks will worry about the ceramic flaking off instead of the aluminum?
I think S&B is highly safety conscious and my impression is that with heat levels these devices use, aluminum is not being "released" during use. Scratches/abrasions should of course be avoided.
Aluminum caps are by S&B, SS that you may see available are 'after market'.
Some folks use the dosing caps all the time in Crafty or Mighty, I use them a lot for car or outings, etc., they are convenient -- but there are also a couple of ways to reduce your load size without using the caps, if something akin to micro is what you are after. Place an oils pad on top of small load, for example.
In general use, I just fill the bowl, it is more simple.
Packing too tight is what causes more draw restriction, and this will also happen if a normal bowl is packed tight. I am guilty of this a lot, I always want to cram a lot in there!
There are a host of calculated risks that go into using any vaporizer, imo. If you have a general distrust of aluminum, well ,maybe this one is not for you.
As an aside, I am always looking at the new vapes and methods. One that gives me pause is the almost complete acceptance of huge variety of exotic woods, often used as a stem, packed with herb and stuck right in the vapor path. I had a career in woodworking and have seen lots of 'reactions' to different woods.
Yeah, I used to smoke from a wooden pipe, but one I made from local fruitwood, not some x-factor exotic.
btw, S&B sitewide is 20% off for 4/20 sale.