I agree and disagree on the idea, so i will refrain from voting.
I disagree because giving 1x kaioken 5% speed would kill the point of using 3, since as you mentioned the LP / EP drain is too high.
I do agree on a change, but in my opinion the change should be on the SP you spend on kaioken.
1 SP (Lv35) - 1.5% speed
2 SP (Lv45) - 3% speed
3 SP (Lv55) - 5% speed