...for either the forms to act as stances without a finite duration, or for Wraith and Lich to have their cooldowns function independently of the other.
Even with the new negative energy spells, playing a PM is going to be difficult, as they will not have the support of anyone else being able to heal them, and will be paying quite heavily for that "bonus" (4 feats, and a chunk of APs). The least that could be done would be to make it possible to actually plan around the ability to be in undead form.
As it currently stands, PMs run the risk of being without healing essentially for 2 minutes out of every 5, meaning that any primary healers in the group are forced to either ignore the wizard completely (likely resulting in the wizard dying) or to accommodate the wizard's decision of taking PM by keeping on top of when the wizard is and is not in undead form. Pale Masters would be the only class/PrE character required to carry around multiple stacks of different types of healing items (Cure Serious and Inflict Serious Wounds potions).
Warforged wizards gain self-healing 24/7 essentially for the cost of 1 point to their spell DCs (and that's not even the entire situation) and with much stronger self-healing than PMs have (Reconstruct, Mass Repair X spells >>>>> negative energy stuff). Would it be so overpowered to allow wizards to either remain in one form all the time, or force wizards to pick up both and alternate between the two if they wanted to be able to self-heal all the time?