I will compare the total potency of my TM vs SCH and WM, I will suppose you always use your skills in time and you don’t have to move with the basic spell speed, for a combat of 5 minutes and dealing always the max potency damage:
SCH real potency power
Bio: 300/18*240= 4000
Miasma: 300/24*300= 3750
Bio II: 300/30*350= 3500
Energy Drain: 300/60*450= 2250
Shadow Flare: 300/30*250= 2500
Broil: (300-(300/18+300/24+300/30)*2.5-300/30*3)/2.5*170 = 11701
Total: 27701
WM real potency power
Aero: 300/18*250= 4166
Fluid Aura: 300/30*150= 1500
Aero II: 300/12*300= 7500
Aero III: 300/24*370= 4625
Assize: 300/90*300= 303
Stone III: (300-(300/18+300/12)*2.5-300/24*3)/2.5*210 = 13300
Total: 31394
My TM "real" potency power:
Time Leak: 300/30*350= 3500
Quake: 300/21*280= 4000
Judgment: 300/25*350= 4200
Space Trap: 300/35*40= 342
Slow Motion: 300/15*75= 1500
Water I + Water II: (300-(300/30+300/25)*2-300/21*3)/4*260= 15906
Total Potency: 29448
The first thing you can notice is the WM has A LOT more damage than de SCH, even more than my TM. It's a half true, since the WM will run out of MP in the middle of the fight. My TM is similar, it has a decent final potency, but what if you use less potency for judgment? You won't be using Judgment at full power always since you need Undo to keep you in the fight, and you need to use it to recover your MP as often as you can.
Your MP recovy is SHIT, you can burn your mana 1 time every 50 seconds, yes... and what? As SCH I can heal the 80% of my mana every 60 seconds with a fairy that makes me heal without cost. The WM has a MP refresh skill, the biggest MP recovery since it has the bigger MP pool and NOW a skill that regens 10% of their max MP every 90 seconds, even the AST has better regen with 1 refresh and with a Ewer Card. Space Trap and Slow Motion are a MP refresh skills if you are in CS, and only mitigate a bit your waste, Undo is really powerful but you have a skill that makes you cast faster with a constat MP price, you need a MP recovy like Undo if you want a skill like that.