User blog comment:B214/Talk About What You Want! 3/@comment-25290120-20141125182448/@comment-1359322-20141127155542

EP becomes stronger with the [King] so if the [King] is powerful, Issei can still be reincarnated. And the reason why i said Ise is not a steal(bargain) because regardless if Ise is weak or strong, Ise would still need 8 Pawn Pieces, no room for barganing there. Yuuto and Saji are different. Depending on the time they are reincarnated, Rias and Sona's EP consumption would be different. If Rias had reincarnated Yuuto lets say in V5, Rias would have had to use two Knight Pieces, but Rias did that with only one. In Saji's case, if he was reincarnated in V9 perhaps, Sona might have to use 6 Pawn Pieces (an assumption), but she did so with only 4. She save 2 extra Pawn Pieces. That's why Yuuto and Saji is a steal, they were reincarnated at a lower price than their current worth.