I agree with rOm regarding the characteristics of sublingual/buccal salvia. I have not tried a tincture specifically, but I don't see why the effects themselves would be any different.
Personally, I get VERY consistent results buccally. I'm not sure what rOm's technique is to know if that contributes to his intermittent success, but after a few tries I knew exactly how much I needed to get 'there' (.8g leaf), how long it takes to for the trip to begin (10-12min), how long it will last (1:15ish), etc.
I LOVE the idea of having a group oral salvia session, but with experienced salvia users rather than novices. In my limited experience of talking people into trying oral salvia prior to smoking for the first time, it seems most people new to salvia do not typically have much success when they try quidding first. Perhaps with a tincture there would be more success, as 'technique' would be less important, but I suspect not.
Salvia quid enthusiast