Ki can be felt, ki can be developed and ki can be used. I'm finding it odd, that one encounter with a ki based school apparently means, that ki does not exist. It is like sailing a leaking boat, and concluding that boats won't float!

There are masters out there who can even use ki to make them selves heavier from a static and unchanged position (In fact we all can). One shodan at my club tried this in his jujutsu days and could not lift a 1.6 m tall japanese guy, and still does not know how this happened. What body mechanic would be able to have this effect?

Personally I have had many encounters with ki, but 95% of them was not in Aikido. When I have got the time, i might post something very thought provoking.