I posted this on another forum and the answer I got there was that a lot of peperomias store water for a time (like you said), but are not drought tolerant like a jade or cactus
would be. Like African Violets though. That makes sense. I noticed that they also have shallow, small root systems like succulents
I know what you mean about the heat. Last summer I burned my two variegated peperomia obtusifolias by leaving them a little less than a foot away from an eastern window. They were two of my favorites, so that really hurt. I was able to salvage some stem cuttings and root two leaves. That was last August. Only two weeks ago did I see a new little plant emerging from one of the leaves. 8 months later! I'm still waiting for the other. Patience, patience... I know I could just go and buy another one pretty cheap, but I want to stick it out. The stems rooted pretty easily. I only have experience with that type of peperomia though. I don't know how the others are. I just got a rooted cutting of Peperomia Dolabriformis about 2 weeks ago. It seems like a very nice plant, so I'm hoping for the best with it.