How to measure the performance improvement that NUMA brings?
You can't on a host with only 1 node. Your query on sys.dm_os_memory_clerks shows you only have 1 physical node (0). The other node (64) is a logical node for Dedicated Admin Access (DAC).

In older versions of SQL Server that were NUMA supported instead of NUMA aware/optimized, it is possible to tank performance when running on large NUMA hosts. Consider this: you have a large server with 4-NUMA nodes (say HPDL980). Query executed from node-0 retrieves a large amount of data which gets cached in node-2. To access that data, you now do at least 2 hops across the CPUs and perform cache-to-cache transfers. They're REALLY fast compared to disk but still a LOT slower than pulling directly from node-0 where the query originated.

Versions of SQL Server that are NUMA aware/optimized will try to keep memory usage within the same local NUMA node to avoid the hops. Even if soft NUMA is further layered on top of this, SQLOS memory node still works with the physical layout presented by the OS. That way, you SQL Server will still optimize for physical local nodes even when they look like different nodes logically. You can also track remote node access from perfmon using the SQL Server:Buffer Node\Remote node page lockups/sec counter.

These are very highly descriptions plus it assumes existing knowledge of NUMA, SQLOS, SQL Server memory management and query execution details. Lots of good write-ups on these areas in the CSS blogs and if you're keen on how all this started way back in 2005, read up Slava's blog (http://blogs.msdn.com/b/slavao/). It's really old but that work laid the foundation for what you see today.