I used to sing with a choir whose then-director favoured Voicecraft. In his version, however:

- sopranos had to sing breathily, with no attack at all. The result was little-girl noises, very flat and generally behind the beat. Many of the soprani seemed to struggle to to reach anything much above the stave... apart from those deputed to beef out the altos.

- altos also had to be breathy, and were left to sing quite staggeringly flat, without correction. For the alto line to be heard at all, the genuinely low voices were fleshed out with a handful of sopranos, who were instructed to bellow with a lot of edge (the director's version of 'singing with a twang'. Singing like this, and out of their natural range, the translocated soprani tended to force their sound by digging out notes. Not pleasant, not in tune, and not remotely with the beat.

- tenors and basses, mercifully, got off rather more lightly. On the whole, they found it easier to sing with an edge without being flat or getting behind the beat... although, to my ear, their notes were as often shouted as sung, and tended to the nasal.

I went to one of their concerts some time after leaving the choir, and I have to say that, as a choral sound, the effect was truly horrible.

Not the best of advertisements for Voicecraft. Somewhere between unhelpful and downright damaging for the singers, to be forced into such bad habits (and many of them did not know enough to know that forcing, breathiness, etc WERE bad habits).