mainMem.writeZeros = "TRUE" solved VMEM fragmentation for me with WS 9.0.1 and Host W7Sp1x64. We are also using mainMem.useNamedFile = "FALSE".
For a 64 Bit VM assigned 2GB RAM - without mainMem.writeZeros = "TRUE" we got Fragments in between 15000-20000 - and now its just 50-150.
Resume from Suspend VM was noticeably faster and we tested this by Removing STANDBY PAGETABLES using RAMMAP.exe - we also monitored DISK I/O Access Bytes using Procexp.exe simultaneously.
Regards