Usually they are fine from my experience unless you are trying to use it on the plane. There is a guy in NY who has created a modular keyboard out of interlocking pieces and a foldup one but I don't think he has the patent yet.
I think that would be one of the greatest things - two 3 octave keyboards that join together to form a 73 key. A locking hinge and an electrical connection between the two is all that would be necessary.
Independent Arranger / Producer / Engineer
Chicago, Il 60622
(Nuendo 3, Native Intsruments, lots of other software synths)
disclosure: I work at Guitar Center but do not speak for them unless otherwise noted.