I'm still gimping along in T5 as well (9 left!!) and I can tell you that I see a massive difference between running Abyss with bard and without....and thats with only a chanter nuking/dotting. Bard adds a ton to kill speed for me....and survivability. More so if I run the wizzie in group. And yes, bard added a ton with or without NS6's and sorc charm.
I run SK, CLR, BRD, WIZ, WIZ, WIZ. The spell damage bonus is noticeable, the mana regen is helpful, the buffer zone (Nilipus) helps me not randomly lose wizards, and the UC'ed damage is respectable with NS5 x2 (and nothing else).
Oh yeah, One Man Band (5.0+ click) is AOE friendlies. Not group, AOE friendlies. That's why it's named as such. One character can buff all those in range (but not necessarily grouped/raided).
-Hate