The leveling just got worse...

er..
Zombies: (Level 132)
145,000 HP
2,529 EXP
HP/EXP ratio: 57.3

Sample mob at Lionheart Castle: (Level 125)
HP: 11,500,000
EXP: 249,360
HP/EXP ratio: 46.11

This isn't counting the exp buff when training with 6 people in your party. Every mob in Lionheart Castle is a boss tagged monster, so having 30% bossing damage would help you. Counting the exp buff you receive at lionheart castle and factoring in party reduction would give you 412905 exp. Buffing the HP/EXP ratio to 27.85 HP per EXP awarded.

I wonder how outdated that thread with the mobs is, since that's where I got the values.

Don't forget that at LHC you can actually be constantly attacking instead of moving around the map trying to get spawn. The more funded you are, the better LHC will be for you, whereas in normal training, funding past a relatively easy point to reach makes very little difference on your exp gain.