you're going to get a ton of different answers here, but since you asked...
my answer is, it depends. i have had many fellow reefer friends who say they're going to upgrade and never do because they think the fish is fine where it is at...
that being said, if you truly plan to upgrade soon, and there is currently a lower amount of fish in the tank, and there is a good amount of mature live rock in the tank, and you keep it well fed, and it is on the smaller end size-wise, you'll be good to go... if not, i would suggest passing.
just my 0.02$