A little late to the conversation, but I'll add some more personal experience.
Of the two blennies you mentioned, the Midas Blenny would be the better option.
In fact, the Ecsenius spp. blennies are the more docile genus in the blenny family. I have kept bicolor, tail spot, linear, midas and pictus blennies and they were all great community fish. Midas blennies are a bit large for the genus and tend to fare very well in community tanks. My current Midas Blenny does great in my 120gal community reef. The only "aggression" it displays is towards my male Lyretail Anthias when the male tries to exert dominance over the blenny; as the blenny will swim with my five female lyretails. And the so-called "aggression" is just the two fish flaring open mouths at each other.
I have kept a couple of the Salarius spp. blennies and they're a bit more hit-or-miss. Some of them have behaved perfectly well, others have been terrors. They often do not like new additions to the tank or other fish that will inhabit the same living space as the blenny. I had added a Starry Blenny to an established tank and it killed two gobies and a Flameback Angelfish before I could remove it; but another fish years ago was very calm and passive. It's a coin flip for me at this point with these fish.
The blennies that you have heard of that may have bitten other fish are probably from the Meiacanthus genus. They're commonly known as fang blennies. When they feel threatened or are attacked, they will bite back and are considered venomous. I have not kept any of these fish, so I'm not personally experienced with their behavior.
It sounds like you're aware of the difference between blennies and dragonets; (not "scooter" blennies; stores please stop ID'ing them as such). Unless you have a tank with pods crawling all over the glass, leave the dragonets to a more quiet environment. The dragonets are rarely interested in any of the other fish, but they are more easily intimidated by the other fish and may not fare well. I had a male Ruby Red Dragonet that did very well in my tank for a year, but even with plenty of available live foods it just up and disappeared one day.
I would suggest the Midas Blenny.
You may end up seeing it swim with your Bartlett's Anthias.