User blog comment:Jopjopjop/Volume 20 Spoilers/@comment-26865730-20150808042203

I agree with all that stated Issei will not want the King piece. I think like Vali, Saiorg and now Cao Cao, Ise will want to stay only with his own power, even as that power evolves with each clash, it is still his.

That being said, if the king piece grants the power-up and the stamina to power it then it is easy to see how our stamina challenged hero might desire it. Draig works by boosting Issei's base stats and Issei pays with stamina. If he could get a hundred time power up from his base and not pay for it, then his body made from GR would be able to handle it.