Juanse has asked a very complex question. There are so many variables here it is really impossible to offer anything definitive by way of answer. One thing is however certain...no matter what you do, you will always a see a variation in the distribution of strength between colonies at any site. I believe there was some research that showed that even within one month of evening up the population strengths within an apiary, the 'normal' distribution had become re-established(PeterB? Randy?).
However, that said, a 'Dink' is a dink and always will be unless something is done to improve the situation, and Allen's recommendation to deal with these is standard management strategy because it works.
The key to Juanse's question however relates to his desire to  improve his overwintering success and minimise losses that occur then.
>I was thinking that by culling a given amount of the smaller ones I was
>going to improve  the winterability trait of my stock and at the same time
>reduce the amount of hives now before the swarming season. During the
>swarming season I will recover from the "losses" and increase in the 1000 or
>so hives I need to do this season to follow the programed schedule of the
>company.
 Certainly culling those that haven't culled themselves during the winter period, and have just scraped through with small populations despite a favourable (less severe) winter season, would on the face of it, appear to be a step in the right direction. I tread with trepidation on that point though, because I have no experience with those types of bee that are used in the northern colder climes, where winter survivability is closely linked to a shutdown of brood rearing and frugal use of stores. Certainly the choice of breeder is of paramount importance here.
If I understand your operation correctly Juanse, your normal culling practice is to dequeen and even up populations in the colonies to be requeened before introducing cells. The only variation to that practice that comes to my mind is to perhaps bulk up the bees (take package bees) from the bottom ranked hives(less than 3 frames of bees) and combine them with bulk bees shaken from the top ranked hives (8 frames of bees or more) and use these to stock the new queen rearing colonies. Presumably this would not impact on the pollination efficiency of the remaining colonies to be contracted to the blueberries, whilst at the same time give the increase in numbers required and help minimise swarming losses?

PeterD
(in Western Australia where the only bees available are Italian type)
 

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