After observing them for a week in my main tank, I can report that Serpae tetras may not be quite what I expected them to be.
[Update: These may not be Serpae tetras.]
I have kept a number of tetras over the years (neons, cardinals, rummynose, glowlights) and I have always found them to be exceptionally well suited to a community aquarium - they are peaceful, attractive fish that bring life and colour to the mid-waters of the tank. While they are strikingly pretty fish which bring life to a tank, my Serpae tetras are far less peaceful than the other tetras I've kept.
For starters, they are aggressive feeders. While glowlights will spit out food that's too big for them (and maybe take a second or third bite at it), the Serpae tetras would not let go of a piece of food once they had a bite of it. They also go after food quite aggressively, even challenging the (must larger) Corydoras and kuhli loaches. Again, unlike the glowlights, which rarely go after food on the bottom of the tank, the Serpae tetras will go in for it.
They are also much more aggressive tetra-to-tetra. They will bully the glowlights just a little, but far more noticeable are the occasional clashes with their conspecifics. Just a few of the largest fish fight with one-another, but as they settle in, these clashes seem more common. I doubt schooling tetras are likely to be territorial, so presumably this has more to do with setting up a dominance hierarchy.