Is there an advantage to keeping the QCTP squared up and rotating the compound vs rotating the QCTP itself?
My take on it is if you use indexable carbide, the tool holder and tip were designed by the manufacturer to achieve what they considered an optimum angle of cut. Orienting the tool 15 degrees or whatever isn't really going to help. HSS is a different story, the optimum cutting angle isn't ground into it... unless you waste a lot of time at the grinding wheel.
Yes, I started out trying to be an artist, rotating my QCTP which ever way caught my fancy. And then I started learning more about indexible carbide, and just stopped wasting my time and left my tool post squared up.
The exception: when cutting threads, you have to rotate the QCTP. You set the compound to 29.5 degrees, and rotate the tool post so that threading bit is perpendicular to the workpiece, and then use the compound to advance the bit into the the workpiece (yes, I know that some people "cheat" and skip the whole compound thing, but you do get better looking threads IMHO).
So, at the end of the day, I would pull those pins and chuck them.
Dorian AFAIK is the only company that sells QCTP predrilled for pins to keep the tool post from rotating. Their brochure says it makes it stiffer. They would also prevent a parting event gone horribly wrong from rotating the toolpost into the chuck. Never seen it happen, but heard of it.