As one additional note, consider that you can only shuffle skills "so long as any knowledge or social skills are not given a higher value by the change" (YS174 for Beast Change, and True Shapeshifting uses the same rules).
So even with True Shapeshifting, you don't have absolute freedom with your skills. You need to define your base form, then you're allowed to let physical and perceptions skills to float up or sink while knowledge and social skills may only sink.
And as mentioned by others, I don't see any reason not to allow a character to take Beast Form twice, allowing two shapes with a skill tree each. A good example would be the classic (Black Court?) vampire power granting the bat form and wolf form. I could even see allowing such a character to take a poor man's version of modular powers, paying a single -1 refresh to have Wings [-1] in bat form and Claws [-1] in wolf form (since the choice is locked to the form, and is therefore not truly modular). This would be a GM call, of course.
And regarding the last two posts, I think it would be fair to require the True Shapeshifting player to have an index card (or some other writen form) describing each form they know, complete with skill set. They can only shift into a form they've written up in advance, in order to prevent delays of the sorts described. They can make as many cards as they want, but need to let the GM look over them before use. (No monkeys with Guns 5 -- unless the base form had it!) I'd probably also require that they only have one version of each form (so no "tracking-spec" wolf, "fast movement-spec" wolf, "combat-spec" wolf, etc, though having a tracking bloodhound, fast movement cheetah, and combat wolf would be fine).
