If you wanna go for cutdown lvl 4 or 5, you would have to give up rocket punch which i think is better for fighting boss since you cant launch them.
Sure you can relaunch that many mobs to do aerial frenzy again but at the end of the Mission Map is the boss which you cannot aerial. So i think rocket punch is better then cutdown. Helps me alot in tutu and toto.
+10agi or +10vit is quite useful at low lvl. which is why i recommand it. At lvl 19, since we are going to reset our skills. so why not use all the skill points instead of leaving it around.
P.S if you like cutdown, max it =) rocket punch is just what i prefer