I thought it was a useful answer, it's pretty much what I'd say.
I don't know of any studies into whether it improves CTR.
The sole skull & crossbones looks quite effective, but the descriptions and titles with the stars look spammy to me, so I probably wouldn't click them. I'd say be subtle, perhaps add something that might be enough to catch the eye without putting people off clicking. Remember Google can change the meta descriptions and titles if their algorithm deems they're not appropriate for the search - another reason not to go overboard.
I can see this getting to the stage where everyone in some SERPs has added a load of symbols to try and get noticed - that's when Google might add it as a negative ranking factor, or just not display descriptions and titles that use it.