The Gibraltar is on Peru, a busy street, is well lit, and not unsafe at all around there. Plenty of taxi's to get you around, and it's on bus routes too. We head there quite a lot, and so far no problems heard, unlike some of the tales you hear from Recoleta, Barrio Norte, or the bar areas of Reconquista at times.
As we said to others, we travel from Avellaneda and San Isidro, to name wo places, as we like the place and the location, but feel free to plan a night out somewhere you know, and feel comfortable in, and people will come along.
Seriously, grab a cab, come to the Gib on Friday, see what the craic is all about, and keep the pre-conceived ideas about the area at home, and see for yourselves.