There is confirmation that SampleTank VST3 now works - http://forum.cakewalk.com/FindPost/3150781
 
Has anyone tried and of the Arturia VST3? I don't think I am missing anything having to run the VST2 versions but it would indicate an improvment in the general implitation of VST3 for VSTi which seemed to be a bit flakey in X3. That will be good when there is a VSTi that actually implements VST3 exclusive features.

They should. I worked with them and resolved all known issues earlier last year. They are also on our 3rd party beta and had access to Platinum.

Arturia's VST3 Version works fine, now.
 
Sonar Platinum / Windows 7 / 64bit