I prefer slower, more meaningful mind control. I want it to mean something when the subject falls, and if the number of harem members is too high then we barely know the characters at all.
I loved Chrystalis because at least we learned something about each woman when they went under. It was a good way to make the larger number more meaningful. The rest of the time, the characters become far less memorable and that takes away from the hotness.
Eh, I don't think Chrysalis gave the characters any more depth than most of the stories on this site, it actually seemed like it gave them less. I'm a bit biased, though, as I tend to dislike that style of transformation (like the clockwork and living blow up doll ones).