i can assure you, the ADD A LEAF will be far worse. i belive the person you are referring to commented back, his shock choice is what stiffened the ride, not the mini pak.
i have had several trucks with Deaver mini paks, none of which rode any firmer. the add a leaf, similar to the overload, limits travel.
the mini pak being additional (possible lift height increase), thinner leafs...flex more during travel, where as an add a leaf (overly arched to achieve lift), takes more effort to flex...i have had a couple trucks with them as well.