Have the rumor about maxed Kaioken's less EP / LP drain ever been officially proven? My DW have 3/3 kaioken and my SK only 1/3, and to be quite frank, the little time I've spend on same dilemma seemed to me like it was indeed maxed kaioken which drained more rapidly.

Yeah. If your generally playing SK only as PvE and / or farming, spending more than 1 SP on Kaioken would be a waste. But indeed, giving it the full go (3/3) -as for 5vs5 goes is strongly reccommended!

Ah that's too bad i don't want faster LP/EP drainage on my human but the bonus attack points are worth it. Well tankers are a different story i guess.

I'm not 100% sure, but for me to see, it actually seems that 3/3 Kaioken drains more EP and LP for the bonus of 300 damage points.

lv 3 has the lowest ep/lp drain, and the biggest dmg boost.

lvl 1 = 20%
lvl 2 = 25%
lvl 3 = 30%

for 5v5 i always use it