Maybe if you calculate the expected base cost of Heartseeker very carefully then Fudo's way could work. But a better HS expected cost formula is needed, and even then there is a problem.
Even if we assume Fudo's way is correct, his result can only apply for the full channeled bonus used (+50%) section. The other results must be wrong. Because in order to get his 357.1 HS expected cost, he input 111.9 HS savings, which itself arose from the assumption that the used bonus is +50%. That's a broken circular logic.
QUOTE(Fudo Masamune)

and if you still insisting to integrate that discount to the calculation, you should put that on the base cost of HS
HS expected cost are decreased by it's natural chance of getting channeling : 469-111.9 (channel bonus used +50%)= 357.1
Base HS bonus (channel bonus used +0%)
IA5 357.1 - 362 + 181 = 176.1 -> 57,408.6 ( ~ lose 64.58MP / battle )
full channeled HS bonus used (+50%)
IA5 ( lose ~64.58MP / battle ) + 58.21 = ~ lose 6.37 MP / battle
Let me try to fix Fudo's method. I propose: HS expected cost = 469 + 469 * (Channel Bonus) * (1 - 47.84%)
Channel Bonus can be as desired, +50% is the example. 47.84% is the agreed calculated chance for Heartseeker to channel itself. The Channel Bonus is already part of this new formula, so it doesn't need to be applied later like before.
Plugging my made-up HS expected cost into Fudo's method gives the same answer I initially proposed. So perhaps I cheated. This HS expected cost formula seems fair to me though. It's a different way of looking at the problem which ultimately gives the same answer in a not obvious way.
QUOTE(BlueWaterSplash)

I am puzzled why I am drained without Spirit Stance. The Settings menu lists my upkeep at 1.55 MP/round. I have +27 Magic Regen per tick which the
wiki formula MP gained per turn = Magic Regen * perk_bonus / 15 says is equivalent to 1.8 MP/turn. Can anyone explain my mistake?
I tested it extensively and concluded the error is in the shown wiki formula for natural regen. My actual MP regen is about 1.38 MP/turn, not 1.8 MP/turn as calculated. I verified that all other things such as IA upkeep seem to work as expected, and rounding error is minor. Infodump follows.
CODE
Level 365, no Spirit Stance
1636 MP, +27 Magic Regen per tick
Protection: 100 MP (210 turns)
Shadow Veil: 134 MP (98 turns)
Spark: 139 turns (124 turns)
Haste: 125 MP (126 turns)
Regen: 281 MP (103 turns)
Protection + Spark = 0.95 MP/round
Protection + Spark + Shadow = 1.77 MP/round
Protection + Spark + Haste = 1.55 MP/round
1636 MP --> 1264 MP --> 984 MP --> 1117 MP
(1117 - 984) / 97 = 1.37 MP/turn
1636 MP --> 1221 MP --> 1265 MP
(1265 - 1221) / 98 = 0.45 MP/turn
1636 MP --> 1273 MP --> 992 MP --> 1163 MP --> 1165 MP
(1165 - 992) / 125 = 1.38 MP/turn
1636 MP --> 1230 MP --> 1285 MP
(1285 - 1230) / 126 = 0.44 MP/turn