I prefer smaller volumes too. With mots c I once added just half a ml to a 10mg vial so the whole thing could be taken in one go.
Just starting out with some T-20 and my gut says smaller injection volumes should cause less irritation. I was thinking of mixing 20mg into 0.8ml BAC so a 2.5mg dose would only be 10 units. Any downsides to using more BAC instead?