Watch the Sussing Barre Chords online guitar lesson by Rich Maloof from Guitar 201: Breakthroughs
A closer look at barred forms of sus chords. The same thing is happening here as with open chords — sus4 and sus2 are messing with the chord's 3rd — even though it looks different. The big benefit with barre forms, as usual, is that you can move it anywhere on the neck as long as no open strings are used.
The nomenclature for sus chords can get a little weird. For example, you might see a chord written Asus4 when it’s really A7sus4, or you might see a chord written as a sus2 when it’s technically an “add 9” chord. Also, the suspended voice doesn’t always cover up the 3rd of the chord — sometimes a 2nd or 4th is added in addition to the 3rd.