I was a fool trying to craft an optimal graph without enough skill and knowledge. So I tried to imitate a skill rotation of Barb 3 variant. There was quite a lot of assumptions and lack of info such as exact skill execution time so I just had to guess based on videos. The crude spreadsheet I made showed some interesting results:
First, regarding SP cost between Lv1 and Lv10. Well, Lv10 Composee uses 2.3x times more SP than Lv1 in exchange for around 30% more DPS. Is it worth it?
The answer is in the second point: It depends on your fighting time which I assumed you were able to evade everything and just stood there and dealt DPS. If the fight is short (less than 2 minutes), you will triumph with left over SP. The opposite is quite bad if your main way of dealing damage outside skill rotation is Composee, you will end up in SP deficit even if your Composee is lv1. The longer you fight, the bigger your negative SP reserve will become.
In conclusion, higher lv Composee is better if you can conclude the fight in less than 2 minutes. If you can’t, just don’t. Try to increase your DPS by attribute and get more Patk

