Steph,
You really need to stop and embrace what I mean by "size differential"...an adult fuzzy will eat a baby volitans, an adult volitans will eat a fuzzy, etc. We kept a couple of small scorps in a SH tank for awhile, and I got away with it because the SH were too big for them to eat at the time.
IIRC, there are some folks here keeping Dendrochirus lions with medium-bodied Pterois species with no issues. If the fish grow-up together, there's even a lower chance of trouble. I'd keep our Mombasa (a medium-bodied lion) with our Dendrochirus and other small scorps/wasps and not give it a second thought, but I wouldn't do the same with our antennata because it came in as an adult, and it's on the hairy edge of being too large, IMHO.
Also, realize that generally speaking, if you obtain juvies, they will only obtain about 75% of their "wild" adult size.
Does that make sense?