It depends what the core is. There are a number of Xeons which are the same core as their i7 counterparts. In this case, I'm pretty sure you're not buying anything extra (I think they even cost the same price). You probably had one of these, if your computer was a standard tower. You get ECC memory, but for most that's not a huge problem.

This system they're testing is a beast that's designed for enterprise systems; they're hugely expensive. You're meant to get perhaps 144 hardware threads, hundreds of gigabytes of RAM, terabytes of storage and a price tag of >$50,000; it's designed for the limits of vertical scaling (and is a job I imagine it does well).

Even if you were to dump this kind of cash, you'd get terrible performance in practice due to the design decisions made behind all of this (memory system will be tuned for throughput not latency, for example) and poor software support (i.e. an OS like OS X would do a shoddy job of scheduling threads, especially across NUMA domains. Linux was terrible also until a few years ago, it wouldn't manage to schedule more than about 30 threads simultaneously no matter the lad).

I'd go so far as to say that you'd expect better performance from a standard tower than you would from this.

In general you'd expect a desktop processor to give you about as good performance as you'd manage to get for developing C++. All of the editing tools are tuned for desktop processors, and there's not amazing parallelism to be had with most compilations (and incremental compilations won't see them at all). Note the benchmarks are for 'total number of kernel compilations' and not 'time for single compilation' :)