One thing i just remembered,whatever noise you make to recall him,one pip or several or continuous,stick to it and never detract from that and he will learn that only means come back and nothing else,if you change it he will get confused,i have had serious run ins with my OH as he doesn't use the whistle exactly the same as i do on occasion ******
I advise people to stick with one whistle pattern when first teaching recall by whistle, but as a dog is proofed with the whistle it won't be confused if you train for different whistle tones or different patterns for the same behavior. With my boy I use a long pip for recall on a 210 and a series of pips for the 210.5. There should be no confusion as long as you consistently ask for the same behavior.
I think it would be very confusing for a dog to be expected to respond to different whistle patterns for the same behaviour even if they are "proofed",especially when you are teaching the dog other commands with other patterns unless i'm missing something, as i don't see the benefit of having several patterns all meaning come back or several patterns that could mean stop.
Ruby definately wasn't as sharp as she had been with her recall and stop when my OH had been using the whistle to a slightly different pattern to me but as i said i could be missing something as i don't work my dog and i only use the whistle for recall and stop.
I also agree with you that consistency is key,but consistency with the same whistle pattern for the same behavior.
You teach one thing at a time, one pattern at a time so there is no confusion and still maintain consistency. If the dog has already been taught one pattern and proofed with that pattern you can move on to teaching and proofing another pattern for the same behavior. The first pattern/command for the same behavior isn't going to slip through the cracks of its brain, because you introduced another pattern/command.
If you don't see the point then don't do it. I'm just saying that it can be done and others, like myself, do it with our own dogs.