I entirely agree with you noticing the snapshot reserve. The more space reserved, the more snapshots you can keep for a longer time.
If snapshots are to be stored for longer time, naturally more space is needed - as more changes to the data occurs. No one in their right mind would use CX4 snapshots (suffering hard from the performance penalty) extensively, therefor it wouldn't make sense to reserve much space for the purpose. This is a lack of a proper snapshot implementation on the CX4, its NOT a "higher-utilization-rate feature".
But the part of your post I don't understand is: "Netapp's are in general slow and expensive (having admined 100's of TB of Netapp and EMC over the years, I know, trust me), but at least they published a legitimate face-off with the SPC-1 benchmark."
You state your belief that NetApp played fair in the benchmark. While providing a higher performance and more useable capacity from LESS drives than a Clariion. Even using raid-levels with protection against double-disk-failures AND using snapshots, the NetApp proved to perform faster than the Clariion. All fair and well ducumented.
I totally agree with you on the "playing fair" part, I just don't understand, based on the referenced test, that you in the same sentence claims that: "Netapp's are in general slow"..... Now, where does that leave EMC then? :-)