Kasha,
Rav Henkin is one of the most respected rabbis in the modern orthodox community in Israel. Like most rabbis, he has some leniencies and some stringencies. And he generally follows his grandfather z’tz’l when he has a specific mesorah from him.
And everyone would benefit from reading his essay, “Contemporary Tseni’ut” in the Fall 2003 issue of *Tradition* in which he brings many sources that commenters here have ignored. You can buy it at the traditiononline web site.