The only man I know who uses "Atashi" (outside of manga) was from Kansai. It is still extremely rare, but would it be more common there than Tokyo or other places :?
I associate men's "atashi" with 落語家 (rakugoka), 時代劇 (jidaigeki) about Edo era, and middle-aged (or more older) people in downtown Tokyo. Not Kansai but Tokyo (however, only of the old days) in my opinion.