New night's silence set = NB's form of BE

Redwyrm

Ppl don't realize that this buff simply not working at all in combat.

So as long as you did first hit, or been hitted - thats it, no more +60% speed for you for as long as you are in combat. You can try go sneak in combat, you can can even go in cloak, which instantly put you in sneak-mode. But neither in crouched mode or invis-mode you will get that speed buff.

So that set obviously help you with moving around, but pretty much useless in combat.
And yes, despite its useless state in combat, don't forget you still use 5 armor/weapon pieces for this set, thus not using something else.

Not wearing night's silence set = 2 useful combat buffs (2x 5-item sets)
Wearing Night's Silence set = 1 useful combat buff, and 1 useful NONCOMBAT buff.