Wizard preparation

[Squirrelloid]

They behave differently mechanically because they are different mechanics.  Retraining is a minor alteration in your character's options.  Replacing a low level power with a higher level power is a significant increase in your character's abilities.

Ok, there are two components to these mechanics:
(1) What level of power you're allowed to choose
(2) How you go about swapping out.

We agree 1 is different between the two of them

However, 2 is described identically in the rules for the two options.  So how that behaves should be the same for both.

You can replace a power with another of the same type

... you can replace any daily attack power you know from your class with a new daily attack power

The textual differences are solely based on the generality of the statements.  Retraining pp powers is expressly forbidden later (so you're limited to class powers), and 'same type' is implicit in the trading up because it handles that independently by type.  In both cases you replace a power with another of the same type, just in one case the level limits change.  So why should the replacement mechanic not be identical outside of allowed level targets for wizards as it is for every other class?

[heffroncm]

I'm not quite sure what you're intending to prove here Squirrelloid. 

If swapping powers only allowed you to swap one power, you would only ever be able to have one daily of levels 19, 25, and 29, which runs directly contrary to the entire idea of the Spellbook class feature.  You would still only be able to prepare 3 class daily attack spells for the day. 

If retraining forced you to retrain all of the powers of a given level, well you could just reselect some of the same ones.

[Squirrelloid]

I'm not quite sure what you're intending to prove here Squirrelloid. 

If swapping powers only allowed you to swap one power, you would only ever be able to have one daily of levels 19, 25, and 29, which runs directly contrary to the entire idea of the Spellbook class feature.  You would still only be able to prepare 3 class daily attack spells for the day. 

If retraining forced you to retrain all of the powers of a given level, well you could just reselect some of the same ones.

I'm just saying they should work the same, without expressing a preference for either metric, that's all.  Because that's what the rules suggest is that they work the same.  Hence why I'm confused that the FAQ says one of them works one way, and CustServe says the other works differently.  That is, if you're a wizard.

[heffroncm]

I'm not quite sure what you're intending to prove here Squirrelloid. 

If swapping powers only allowed you to swap one power, you would only ever be able to have one daily of levels 19, 25, and 29, which runs directly contrary to the entire idea of the Spellbook class feature.  You would still only be able to prepare 3 class daily attack spells for the day. 

If retraining forced you to retrain all of the powers of a given level, well you could just reselect some of the same ones.

I'm just saying they should work the same, without expressing a preference for either metric, that's all.  Because that's what the rules suggest is that they work the same.  Hence why I'm confused that the FAQ says one of them works one way, and CustServe says the other works differently.  That is, if you're a wizard.

They really shouldn't work the same, for a wizard.  It would be highly detrimental to the spellbook mechanic.  That's exception-based rules in action, the spellbook changes the way retraining powers and replacing powers works.  The PHB does a poor job of getting this information accross, as it is all implied and nothing is specified.  Customer Service is trying to clarify, one of their jobs.