I also see my 6 core MBP under 100% load at times, and I work with more "standard" stack of ruby/python and swift.

But from what I read (on barefeats benchmarks, no less) clearly shows that Xeon CPU is inferior for those use cases to fastest Core iX CPU.

To put it in simple terms, for peak loads choose Core iX. For heavy, long term loads choose Xeon.

"100%" CPU utilization means very little with modern Intel CPUs and TurboBoost. Intel CPUs have the headroom to clock much faster than base clocks but often can't sustain due to thermal constraints.

Using a desktop processor with more thermal headroom (with adequate cooling) would presumably be much better bang for your buck than increasing core counts in an already thermally-challenged laptop.