Hugh, I've tried to use tequila only. I had a hard time boiling off the alcoholic taste... I didn't like the tequila taste in the sauce at all. I added water to help boil off the alcohol, but found that after simmering the peppers so long the flavor wasn't to my liking. I think it would have done better with fresh peppers as opposed to smoked ones that I used.
I did find that tequila produced a very smooth flavor. I think it would work well with citrus tasting peppers like habaneros. I'm going to try it again here soon and use mostly vinegar... adding the tequila for flavor not liquid base.