@Kev: I noticed that the sub-3-second catches are a result of both askew ken position and a hard landing. So try to throw/catch it as straight as possible and catch as soft as possible.
Not that I'm an expert, but maybe it helps.
That difference with lunars is the same with me, I have no why. Although I do notice that a stilt more or less 'clicks' into place, where a lunar has to be caught in the right position at the right time.