The changes are (taken from this blog post)
So what is new in 1.6.0?
First of all, the UI reflects Virtual Server terminology. Both Paul and I had used a mix of Virtual Server terminology and internal (SDK) terminology. To reflect the terminology used in the web administration UI of Virtual Server, the terminology of VMRCplus has been updated.
Second, VMRCplus now offers configuration of scripts on both the Virtual Server and Virtual Machine level. This was missing from the previous release.
Third, VMRCplus offers configuring promiscuous mode on the network so you can trace traffic in the virtual switch. This is something Virtual Server does not offer in the web administration UI.
Of course there have been minor enhancements like storage of Console Manager coordinates, conflict handling when a shortcut already exists (something Virtual Server fails to resolve).
The COM and LPT port assignment logic has been fixed (most of it did not work).
The x86 installer package no longer installs on x64. This has been done to prevent issues with 32-bit VMRCplus on 64-bit Virtual Server.
Error handling has been enhanced and several issues have been fixed.