It does work. I also use apple wood in the smoker. It really is great. Especially on humpies!
I use 1/2 cup of salt, two cups of white granulated sugar and two cups of brown sugar. The kicker I put in is powdered Teriyaki. I also use the apple in my Bradley smoker.
We have our Puget Sound Anglers State Board meeting 6 times a year on Saturday mornings. I brought a batch of this and slipped it in beside the donuts. It went way before the donuts and everyone wanted the recipe. Lots said it was the best smoked salmon they have ever had. Humpies smoke really well and easy as they are thinner fish. Makes candy out of it. Thicker fish seems to take longer to brine and smoke, but well worth it.
I have used the apple juice before too. Outstanding results. Also use it to put out the flame when BBQing instead of water to knock the flames down. You will be surprised how much of a sweet flavor it adds.