[Autumn]

I would say that summons staying after defeat is very advantageous for them and not in the wrong way, given that it can be actually very thematic. But given that this system exists from before GR was even a thing, and FP values have inflated by a fair margin since then, some of these systems may have become a bit strong, I think increasing the maintenance costs by double is reasonable, that way the youkai can persist after death, but not for a terribly lengthy amount of time.

It should be noted that anything beyond that starts to become unreasonable, as it should be noted that summoners are already at a disadvantage when dead obviously, not only losing access to momentum each turn they are incapacitated, but also future momentum through the badly beaten debuff, as well as FP Regeneration halting when you are not alive, which when you're gaining 20-30 each turn....that starts hacking away at their youkai upkeep already.