So- they didn't do the study on guppie's waste, but it is still fish waste (processed and expelled food)- but check this out
FishPoo
Just some food for though-but it says there is 2.54% Phosphorus. The fact that the guy at YG wrote that on his site also kind of makes me believe it as he has a Doctorate in Microbiology and biochemistry...(plus has worked in aquaculture for 50? years)
I'm not saying what you said is untrue- I'm just doing some more research on my own and thought I'd bring that study to you to check out.
No-I'm sure it could be argued that a few small fish is not ENOUGH for a tank full of plants-
Off to read more!
I'm glad you got the wheels turning...
As for fast and slow tanks- I have 4 WPG, and injected co2 (though I used to run Carbo-Block (HATED it) and I have VERY fast growing plants (almost too fast-it's a pain in the neck)