I haven't seen this posted anywhere as far as I could see, so thought I'd put it down here for my own reference and anyone else who'd like to see it.

WHM and AST MP
Base MP: 13878.9369526
Each point of PIE gives an additional 3.4282983 MP

SCH MP
Base MP: 13319.4149
Each point of PIE gives an additional 3.2896750 MP

I actually don't know if the amount % of MP restore per server tick while in combat has actually changed. I'm personally a little disappointed in the amount of MP each point of PIE gives given the increases in spell costs due to level.

Extra tidbit - each tick of Lucid Dreaming provides 960 MP back to the user. I haven't done an actual test on The Ewer but it should give back 600 MP per tick as a 50 potency Refresh versus Lucid Dreaming's 80 potency.