Also PFA is the Volmer.
The Kingfishers and Volmers are pretty margin in therms of water performance - their power to weight ratios are poor and 2 up will struggle to get off the water.
The Osprey is more sprightly but reputedly is tricky on water - high lift off and landing speeds and little freeboard. Compared with a decent float installation there are too many compromises.
The certified Teal is somewhat better on the water but is very heavy and so again the performance is nothing to write home about.
I had a reasonably good look around a couple of these aircraft and eventually decided floats were a better choice.
Although if someone could get the CZAW Mermaid through the PFA then there might be a real light amphibian option - having seen them at the factory I was really impressed.....