It is clear that enabling caching/buffering is very beneficial to the specific workload tested in this article. Cache led to much higher disk usage and, as often the disk subsystem is the weak link of any server, this mean higher potential consolidation ratio.
The story don't ends here, obviously: sometime RAM capacity plays an even bigger role in defining max consolidation ratio. And Linux is very well equipped in this area, thanks to KSM.
Anyway, anything that increase disk speed is surely welcomed ;)
Have a nice day!