Virharmonik has two very intriguing choral products, one of which is scheduled to be released at the end of November 2013 . . .
Soloists of Prague, Voices of Prague (Virharmonik)Both of these products have a phonetic language, which is used to create the words sung by the soloists or choirs, and I like the strategy used for the phonetic language, which is similar to shorthand and the ways choirs actually sing . . .
When I was in a liturgical boys choir, the choirmaster taught us to sing "egg-shell-sea-us" for "eccelsias", so that it would cut through the massive reverberation in the cathedral, and the phonetic language for the Virharmonik choirs is similar, where the key is to focus on the way you want the words to sound rather than on the way they are spelled in English . . .
You need to use a sustain pedal to hold some of the ending sounds of syllables, and there are additional uses for the mod wheel, so this might require doing some of the work in a DIgital Audio Workstation (DAW) application, but I think that the basic singing can be done with music notation in NOTION 4 and then can be enhanced after you record it as MIDI in a DAW application, where you have full access to all MIDI CC stuff . . .
Voices of Prague is a bit expensive, but Soloists of Prague is not so expensive at "pre-order" pricing, which is fabulous . . .
Fabulous! 
P. S. Miroslav Philharmonik has nice choirs and a small set of specific syllables and so forth, and you can get a bit of clarity when you understand the rules, although with only {do, re, mi, fa, so, la, ti, ah} there is not so much you can do to compose words, really . . .
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NOTE: I think this sounds very realistic, except for the last note, where I forgot to add a note for the sopranos, hence the last note sounds more like a 1960s Farfisa Combo Organ, but so what. Once there is a 64-bit version of SampleTank (IK Multimedia), all the IK Multimedia virtual instrument sampled sounds will work in 64-bit mode in NOTION 4, which should happen in the next month or two, based on what the IK Multimedia folks are saying in the IK Multimedia FORUM . . . ]
NOTION 3 ~ Multi-Channel Multi-Stave Miroslav Philharmonik Choirs -- YouTube music videoReally! 