I have a Fivemega/wonderlite single cell body. It can hold an 18350 and I don't use cr123s in it. But it can take them.
I have a Vital Gear FB1 body with VME head and a MD1 (from martindwhite over in the marketplace) I like them both. The FB1 only takes cr123 or 16340 li-ion cells and is very small. They only take Malkoff dropins (as far as I know). But that is ok because Malkoff dropins are great.