but when I first read about the double screen, I immediately thought it would be very easy to use for both swarm control or for splits. Again, I have no practical experience with either. My guess is the easiest way to do a split is the "walk away". What do you think?
First of all you need to take a step back an evaluate the intent of the operation. For a commercial beekeeper, the double screen board is most definitely a useless piece of equipment. But likewise, cell bars, cell cups and rearing equipment are equally useless to a backyard beekeeper with just a couple of hives. So just because one beekeeper finds something as "fluff & over-hyped-crap", doesn't mean it might not be important to your methods.
Consider your average hobbyist with 2 hives. I would beg to argue that the double screen could be one of the most valued pieces of equipment.
I can't count the number of times I have heard....... I just spent 20something bucks and recently requeened one of my hives and now it is queenless. It has no brood and I can't get another queen or don't want to spend another 20something bucks. What should I do?
Well, for someone with a bunch of hives and resources available to them, it is not a big issue. But for a guy with two hives, where 50% of his apiary is in jeopardy, it is not as easy. He can rob some brood from his strong hive, hoping it doesn't set it back too much, but it will be close to a month before a replacement queen starts laying and another month before brood starts hatching. That hive has quite the challenge in front of it to get strong enough for the winter, let alone have any surplus. Or he can spend the money and try to get another queen if he can, and hope thing work out better, but now he risks a laying worker and another 20something bucks blown. Of course that brings up another subject of the "queen introduction frame" that is equally considered "fluff & over-hyped-crap" by some, but you will find many here that have saved a hive with it and swear by it.
Wouldn't a better option be to just restore the old queen and brood she has been laying? Unfortunately, the standard practice for requeening is to kill the original queen first and then attempt to introduce the new queen. At that point there is no turning back and any issue with introducing the new queen, the quality of her laying, all leads into the situation above. But with the double screen, you always have the option to restoring the original queen right up until you decided you are happy with the laying of the replacement queen. Not only that, but you get the advantage of two queens laying in the hive during the induction period.
Of course if you are content with doing walk-away splits, this might not be applicable to you. But a lot of folks stay away from emergency queens and purchase reared queens, so it does apply to them. With emergency queens, you have a whole different set of risks. http://robo.bushkillfarms.com/can-you-afford-emergency-queens/