Good reasons but I wonder is the current/new generation 12-core Mac Pro inadequate for this? It could be better but it still seems to serve its purpose.
Depends on what you're doing. I'd be satisfied with a 12-core Mac Pro for everyday development--but if a 128-core Xeon were available I'd take it gladly.
When I was working on quantum state diffusion, it took many hours on a 24-node cluster for a single run. In many of these tasks, the problem will expand to consume all reasonably available resources; more cores allow greater precision, wider sampling of parameters, higher fidelity, etc.
