4 vocals
I'm currently working on a song which I am putting some of these techniques to use on.
In addition to the main vocal I have recorded a monotone heavily compressed whisper, a high pitch version of the lead (same notes higher octave) and a double of the lead but lower in the mix as suggested in the previous post.
Gettin the righht blend can be tricky, but it seems to work really well in getting the vocal more powerful and clearer.
The only difficulty is theose word ends, if you don't finish all the lines spot on then it's noticeable with like and echo as each line finishes a millisecond or two after the other, most annoying. Also it seems to boost the 'SSS' sound too much. I don't have a de-esser ;-(