The 2.1 alpha SL client is out, and it supports voice morphing. With it, you can rent any of several "packs" of five voices, L$750 per month per pack. The packs that exist are "Scary", "Feminine", "Masculine", "Tiny", and "Techie".There's a page with a link to "Voice Island" and a video demonstrating some of the voices. I watched the video; it doesn't demonstrate all of them, just a selection.
I guess there's an "uncanny valley" effect for voice, too; the scary, tiny, and techie voices don't fall in, but the feminine ones in the video certainly do--they sound metallic and phony. I hope the voices improve.
UPDATE: Upon reflection, that metallic sound reminds me of an inexpensive pitch shifter I once played with. If that's all that's being done, it can be easily reversed, and in any case the effect has a distinctive sound, easily recognized. It will carry as much stigma as not using voice does now.
UPDATE: Prad Prathvi put up a post embedding a video that goes through all the voices, and listening to it I realize that people are going to want to stack them. If they've found some voice that they like, they may well wish to modify it further with "radio" or "intercom" to get that effect on their preferred voice. I wonder whether that will be possible.
YET ANOTHER UPDATE: I've submitted JIRA entry VWR-19885 to request the ability to apply multiple voice modifications. If you'd like that ability, you may wish to vote for it.