Yes, I totally agree. From what I know SOV has a very interesting pallete of sounds like gregorian chants and boys choir very sutable for slower passages. The vota on the other hand seems to go more for that agressive choir sound.
The bottom line is, when it comes to choir samples there isn't a complete package out there just yet (maybe in the future with VSL choir there will be), so the best option right now is to have the 3, but if you are just looking forward to composing slow choir passages then sov is for you.