Additionally, as you have chosen GPU skinning, you must be sensitive to exceeding the number of constants registers by providing skin partitions that contain too many bones. A skin partition is a sub-section of a polygonal mesh (possibly the whole mesh) that is influenced by a subset of bones or textured with a different texture. Therefore your assets must not have skin partitions with more than 50 to 60 bones per partition (for 256 constant registers VS2.0). If your model's skin partitions are approaching this limit, you are again forced to serialize rendering in order to set each skin partition's bone palette to the constants registers prior to rendering.
Just to point out that (under D3D10/11) if you use a generic buffer object (as they use in games such as BF3), you may have several megabytes of data at hand and you don't need worry so much about the bone count and constant buffer size. Of course, less bones typically is always a good thing.