Thanks again! I really like the I Am Setsuna way of handling side effects for healing moves you mentioned. I'll have to experiment with that.
Since OT takes the place of MP/SP, and there is no item system to "replenish" resources, a cap is a little tricky. Right now, the strongest offensive skill requires 40 OT and the strongest defensive skill requires 35 OT. However, a cap to "natural" OT gain, but still allowing characters to use their OT-passing skills to bypass that cap could work. I'm not sure how far you've gotten, but Isaac and Jean have a way to share or distribute OT with others while Sparta transforms it into bonus damage. Other characters will be able to utilize it in a similar manner as well.
Also, do you mind letting me know which fight(s) you felt the game spiked in difficulty? I'm interested in knowing which encounters players found most difficult for balance purposes.