I did a couple of recordings with Zero Boy, who is known as a live performer who uses vocalized sound effects. The project involved sections of James Joyce's Ulysses, which ZB read and provided sound effects for. As the point was what he brought as an artist to the reading, I did not modify any of his sounds, though I did layer them (he provide various elements for me to layer) and mix them appropriately. The recording was done in a voiceover studio with a U87 to Pro Tools.
Based on this experience, I would say that vocalized effects are their own category and will not sound the same as typical FX recorded in the field. This may or may not be appropriate, depending on the project.