Hmmm... I find it disappointing that this is not mentioned anywhere on the description page for VEP.
Just looking at the first paragraph here feels like false advertising in that it fails to mention the Mac VST shortcoming:
"Vienna Ensemble PRO 5 is a cross-platform MIDI and audio LAN solution that works universally on Macs and PCs, hosting Vienna Instruments as well as third-party 64-bit and 32-bit VSTi/AU plug-ins. Use it as a host on the same computer as your sequencer to integrate all your 64-bit and 32-bit instruments and effect plug-ins from third-party manufacturers (such as Spectrasonics, Native Instruments, Waves, you name it), or use it as a master-slave solution with multiple Macs and PCs, all connected with a standard Ethernet cable. You can easily route the audio streams of a whole arsenal of computers back to your main machine without the need of external hardware. The Preserve function keeps all of your templates and samples loaded while switching from one project to another. As a Pro Tools user you may integrate your favorite AU and VST plug-ins in your sessions!"
VST plugins are mentioned twice without mentioning "*Windows only" or "*not available for Mac".
I would think it basic courtesy to apply these footnotes.
From the features page:
"3rd party VSTi/AU hosting (multichannel) – Instantiate Vienna Instruments along with other 3rd party VST and AU instruments from Spectrasonics, Native Instruments, and more; Vienna Ensemble PRO 4 works with nearly all available VST/AU plug-ins and supports plug-ins with multiple outputs. Please make sure to use the latest versions of your software."
Again there is no indication in this statement that VST plugins will not work under Mac. Any mention of VST plugins used in VEP should should be footnoted with the proper information.
Finally, at the bottom of the features page we get this:
"Inserts for AU (Mac) and VST (PC) effect plug-ins."
I am very impressed so far by the quality of VSL products, but I must be adamant about not accepting borderline-deceptive wording in product descriptions.