Have any VAC owners tried any KT-88's

YES- Svetlana(AKA Winged 'C'/SED St Petersburg)) has been making KT88s since(AT LEAST) 1999. I was using their EL34s in my ST-70, over 16 years ago.

There's no confusion. Some info: (http://www.stereophile.com/news/022304svetlana/#) It is important to know from whom you are puchasing tubes though, and whether those tubes are being honestly represented. There are some Russian tubes out there that are less than great. I've been dealing with Upscale Audio for years, and all of their Winged 'C's are fresh from the St Petersburg plant(no risk).