One of the advantages of the MIpose injection system is that you need not leave anything out, it sits in a distant folder until you want it in. You don't have to make the choice, the user does. All it costs is the few lines the slot adds. I am betting that a sloth for every V1 morph every made would take less space in a CR2 than one V3 head morph that moves every point. So limiting the number of slots is false economy.