I agree, some are falsifiable, but just saying that the particle only exists during measurement is different.
By definition of the word, we can only be sure of a particles existence in this world when we detect it, so, as I said, what do we gain from this perspective? It is not falsifiable and doesn't actually tell us anything useful, it's just semantics.
I think simply by the fact that detecting a particle tells us that future detection of it is possible (if we know roughly where the particle is going) then we should consider the particle to be real after the detection also, since if it no longer "existed" then we shouldn't consider a second detection of the particle to be in any way related to the first detection because that particle doesn't "exist" anymore, yet the two events are clearly related, and the particles existence, to me, existed in between the two events.
But as I say, that's just my stance, and is as unfalsifiable as Aage's description.