This question depends on what you think of zoro's mastery of enma thus far.
1) If you think that zoro has mastered enma, then yes, it is a power boast to zoro.
2) If you don't think that zoro has mastered enma, then it doesn't add much to zoro and shusui is probably a better blade atm.
3) If you think that he is 50%ish there, then it's a tossed up.
Given the brief time that zoro has spent on enma, i am leaning towards option 2 and 3.
Shusui is also a legendary sword + black blade, so i dunno why people think that enma >> shusui