Ask an Aran thread.

# Max Booster or Combat Step?

This is personal preference. You should get level 15 booster for the +3 speed, but after that is just more time. In my opinion, Step is pretty useless so I would leave that as the lowest I can whilst the other skills in 1st job are maxed.

Indeed. You have the choice of maxing 3 of the 4 skills, and you're going to be slacking 4 points total on whatever you leave out. Preference I suppose, step is very useful @ higher levels for getting in-between gaps of monsters faster to keep your combo going.

Basically, what you'd lose with Max Booster is a larger step and Max Step = Shorter booster.