IN THE MIDDLE of the designer ghetto, there is a tiny but elegant second-floor dance space, home of the Mary Sano Studio of Duncan Dancing. They can squeeze in maybe 50 people for their periodic performances. For her annual Isadora Duncan birthday concerts, Sano has been smart enough to invite guest artists to supplement her all-women ensemble. It's usually an eclectic mix – and be prepared not to have a lot of move-around space. Last year G. Hoffman Soto, a dancer and teacher who has been working in the Bay Area for 30 years, was a revelation. A subtle, athletically powerful improviser, he was breathtaking to watch. He is enough of a reason to head down to Sano's studio. Also performing (Sunday only) are Koichi Tamano, Hiroko Tamano, and Harupin-Ha Butoh Dance Theatre. The eighth annual Dionysian Festival provides an opportunity to see these exceptional artists close-up, in an intimate setting. Completing the lineup are koto player Shoko Hikage and Bharata Natyam dancers Natasha Dar and Zarain Dar. Sat., 8 p.m.; Sun., 3 p.m., 245 Fifth St., Studio 314, S.F. $13-$16. (415) 357-1817, www.duncandance.org. (Rita Felciano)