If you make the spell operate like it does from the book, you don't get all the "super powers"" of the creature anyway. You get the stats, and the HD, AC and such. No Confusion gaze no true seeing no regen etc etc etc etc.......that stuff, is all in the field of the Shapechange spell.
Now, if the Casters can't handle a minor Iota of what the Fighter types have to deal with constantly, I say tough cookies. The Truth is, it IS out of Whack, especially since as a Fighter I certainly haven't seen any +2 weapons out there for me, but the kernel of the entire argument now is this (Oh and for the people out there, YES I still want Spell Components).
It's not the Duration that's really the issue. It's that they Can't Solo unless they can keep the old duration.
Polymorph should be the Shape. Just like the book spell. You get the Stats, and the AC, the heal hitpoints like a Rest and the hitpoint Boost per the Shape. THAT's a pretty good darn chunk of ability for a Mid Level Spell, Umber Hulks and Trolls got some pretty good Physical stats even Without their "super powers".
Shape Change, IS the power spell. It's 9th level it should provide serious power.
Shapechange
Transmutation
Level: Animal 9, Drd 9, Sor/Wiz 9
Components: V, S, F
Casting Time: 1 standard action
Range: Personal
Target: You
Duration: 10 min./level (D)
This spell functions like polymorph, except that it enables you to assume the form of any single nonunique creature (of any type) from Fine to Colossal size. The assumed form cannot have more than your caster level in Hit Dice (to a maximum of 25 HD). Unlike polymorph, this spell allows incorporeal or gaseous forms to be assumed.
You gain all extraordinary and supernatural abilities (both attacks and qualities) of the assumed form, but you lose your own supernatural abilities. You also gain the type of the new form in place of your own. The new form does not disorient you. Parts of your body or pieces of equipment that are separated from you do not revert to their original forms.
You can become just about anything you are familiar with. You can change form once each round as a free action. The change takes place either immediately before your regular action or immediately after it, but not during the action. If you use this spell to create a disguise, you get a +10 bonus on your Disguise check.
Focus
A jade circlet worth no less than 1,500 gp, which you must place on your head when casting the spell. (The focus melds into your new form when you change shape.)
Now if we look at that, It's a good spell as a 9th level spell should be. It's component is a Focus, something that isn't destroyed upon casting and could easily be something incorporated into a crafting system to make it. The Duration is 10 minutes per level. It also comes with a WEAKNESS, that is not in the NwN version.
You LOSE, any supernatural abilities of your Own at the time you shape shift. You ONLY, get what the Form gives you. That means when you Uber buff, cast all your support invisowhatzit acid sheath pile of spells, and then Shape Shift into an iron Golem, the Spells go POOF!
The duration for Polymorph for example is 1 minute per level. 1 minute per level and a cocoon that would come under the *component bag* option. Poof for 1 minute per level you got stats and AC exceeding any equivalent fighter. Shape Change is a 1500 gp component that isn't mulched, and for 10 minutes per level, you get a Creature form and all that creatures abilities (granted you lose anything else you stacked on top of it before you shifted shape), still, both spells retain Power, considerable power, but Acquire Balance.
Going by the book bring the playing field more into balance with not only the other classes of the game but with the Setting. Other spells got the Axe for similar reasons and they've been more then workable. Only reason this ones getting noisy is it curtails Caster Soloing, Caster Invulnerability, Total Caster Superiority, Caster Exponential Power Creep once that spell is gained, and Caster Stomping the Player Base into the Mud.
~Rex