I've never used a kat kabin but if I had the money to buy one I would love to try it. They are supposed to be good.
I would recommend that you provide the cats with a few different alternatives for shelter as you never know what they prefer. You can make fairly simple home made cat shelters yourself. I'd get a couple of different kinds in different sizes. If you have a garage you can open up for them that would be great too. You can leave the garage door open just a few inches. Put some food right by the opening for a while to lure them in. In the garage you can put some plastic totes or boxes with a heated cat bed in them. If there are several cats you can make a little larger shelter or use a dog house and put an outdoor heated dog bed in it. Both the cat or dog bed should be a Lectro heated bed of the hard variety. You can also put these heated dog or cat bed in some sort of shelter outside.
Whatever shelter you have make sure that it's insulated and sealed not to let out any hot air. Once the cats have gotten used to going in to the shelter you can put a flap over the opening to keep the heat inside.
If you have a porch or something where the cats can go underneath it would also be a good idea to make up a little nest there. You never know where the cats will choose to sleep during winter. They may not choose to sleep where you think they should. Who knows what's going on in those little heads of theirs

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Here is a great site with ideas for cat shelters and instructions on how to make your own (some are really easy to make while others require some skill):
http://www.indyferal.org/index.php?page=shelters
Another thing you should think about over winter is the water issue. You have to provide the water for them as they can't find it anywhere but of course putting water outside in the winter will soon leave you with ice. So the best thing is to buy a heated water bowl. They are about $25. You can get an outdoors extension cable if needed. You can buy the bowl in most well stocked pet stores or online.
Also keep in mind that cats need more food during winter.
Are you doing TNR with the cats? If not you really have to start or find someone else who can do it. Otherwise you will soon have twice as many cats or more.
Thanks for caring about the kitties