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.