(I assume this is directed at me.) This is not a difference in perception, at all. Judo, when everything falls into place, will have the same "aiki" moments. The main obstacle to aiki in Judo is that you're practicing Judo on someone who knows what you're doing and is using the same training to counter it. In styles that take a pure-aiki approach, they only practice to work with that pure flow. Some aiki arts (like NGA) split the difference. We practice what I call "Judo style" versions of many techniques. These are versions that work with or without aiki (like Judo techniques do). They can be countered (like Judo), but are effective against unskilled counters (like Judo). We also practice pure-aiki versions of some techniques, which we would only use when that certain feel is there - there's zero resistance, a gap (what I refer to as "the void") in their structure, which allows us to effortlessly execute the technique. We'll almost never find the latter against another NGA practitioner (nor, likely against anyone with similar training), so we'd depend more on the Judo-style versions.