It's not really to do with difficulty, but rather because paradox adds are only given to dexterities that are "full" - while a far reverse whirl or a far dyno do have a full dex, it's an artificial full dex - the bag passes in front of dexing leg in one direction and then back infront in the other direction, and then behind. You could do the same (downtime wiggle style) thing with a butterfly, and do you honestly think infinity should get a pdx add? Artificially making a dexterity full in that manner doesn't give it a pdx add.My experience is that reverse whirl requires a much bigger hop. I usually only have to hop during dyno when I either set too high, too strangely, or I am hitting it from a dive or "paradox". Don't get me started on how silly I think it is that reverse whirl and dyno don't get paradox adds. So what if they are easier.
I agree that for a normal dyno, there should be very little hop. For a far "pdx" dyno, I'd say the most important thing is to hop and twist slightly immedialty after the set, so that the bag is then positioned in the same place as a non pdx dyno, and then just do the same thing as normal. The same rule applies for all farside moves; set and get into position immediately, perform as normal (maybe slightly faster - depending on the move).