What I read and heard about polyandry, it mostly is a complicated relationship that doesn't make the women in the relationship very happy. On Earth I think almost every poly-relationship is man with a couple of women. Man don't like to share their wife/wives, this is a general trait, seen in every culture. So I kind of liked that Honeybee is refering to this complexity in her fic.
I've actually been doing some research on polyandry for a potential nonfiction article - and incorporating it into my story. For the most part, what you say about it usually being males with more than one female is true and it's almost always really sketchy and weird and bad for the women. The groups that practice this seem to be on the political extremes. Right-wing religious people such as the FDLS tend to practice polygamy - the man is the head of the "family" - and it's all about having as many children as possible. This are called "Vee" relationship - the man has sex with the women but the women don't (openly) have sex with each other. On the left wing extreme, you will have new age-y and hippie like cults that practice polyandry - where everyone has sex with each other. Again, it generally happens that there is one man and more than one - usually only two, women. This is called a "triad" - and the implication is that the man has sex with each of the women and the women also have sex with each other - and they share a bed together. But most of these relationships do have a dominant male - the so-called liberal cults still seem to put women in their place. However, on the new age side, it is much rarer - but you will find women at the center of triads and vees. It does happen.
The strangest subset I found were "accidental" polyfidelic relationships. There were triads and vees that didn't form from religious or spiritual ideology or even sexual perversion masking as religious ideology. I found a man who has two wives - prior to that, he was married to one of his wives and they were close friends with another couple. The man in that couple died. Somehow, in the grief process, the widow got folded into the relationship between her two friends. I interviewed the original "wife" and she said that once she and her husband got together with their wife - they considered their marriage dissolved and the three of them equal partners. They got new rings, had a ceremony and sleep in the same bed. They've lived this way for 15 years. I also met a woman who was dating two men casually ten years ago - and they kept dating and kept dating. And finally - they all moved in together - but in that case - the two men don't have sex with each other - just with her. But they do share a bed and all have rings. She's not legally married to either man, because she was never able to choose.
Weird? Yup. But the people in cult-like situations that I spoke to sounded nuts to me. The second group? They aren't nuts. Eccentric? Oh yeah. I was surprised to find such relationships existed. But they do. I'm still working on the research for the article - it's going to take time - but I've already made the early conclusion that the poly relationships that are put together out of ideology are creepy - the accidental ones? Not as creepy - just strange. And not something you could go looking for - they just sort of happen.
But anyway, this is my round about way of agreeing with you that most polyandry type relationships are generally bad for women. But, the way I set up Andorians - is that there is one of each gender in the quad and they are pansexual - I'm still working out how this would all work authority - wise - but I have this idea that they are free to screw around, thus Shran and his wife Nata making a play for TnT, until the quad is complete. Then, they are expected to stay faithful to one another. I made that part up.
But I totally agree that because of the mating bond, Vulcans would be very monogamous (unless, as I said, in a life for death situation) - and any kind of polyandry would be difficult for them if they could only bond with one person. And even though Trip was flirting with the Andorian woman - he's very attached to T'Pol - not just because of the bond but because there is such a thing as a monogamy gene in humans they think - and Trip strikes me as someone who has it in any universe.
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