IME and from I read, they are close to the most common P. blochii in all regards. Mine three sometimes hung together other times swam on their own. I don't think they need to be kept in groups but it is always nice to see the dynamics of a group (unless the fish fight, which should not be the case here).
$45 is a bit steep but still within the norm given their infrequency.
I got mine in 2008.
Just as with blochii, they will eat small tankmates. They don't touch anything that does not fit in their mouth.
Have you read their profiles on PCF, SeriouslyFish, etc.? They are not that rare that their descriptions are hard to find. I mean, whatever I read about them, I found true in the three I had. Unfortunately, our love affair didn't last over a year (I lost them during my move from upstate NY to FL). Mine grew from ~2.5" to ~4"-5" in the year I had them. I wish I could tell you more and how 12" ones behave but that's hopefully in the future.