This new whitepaper addresses the question if one should do a 1:1 consolidation or putting more than one server into a zLinux guest from a performance perspective. The sweet spot for the setup used here was at 10 JVMs per guest.
It also looks at the alternatives for sharing the application binaries between guests using Discontiguous Saved Segments (DCSS) and shared z/VM minidisks. Here it turned out that starting from 10 guests the DCSS setup was more efficient.