Nice work, it's great to see this data pulled together in a nice write-up!
I think the usual problem is deserializing or serializing more complex objects, however. For example, how about ReconfigureTask() where you add a new NIC to a VM? Without the object types, hand crafting the Soap objects can get pretty complex. Particularly if they don't follow 100% standard (which some due, such as ManagedObjectReference).