I guess it is personal preference. I prefer not to use one because I haven't really had the need for it. The area that I hunt has lots of shells mixed into the sand and most of these would collect in the sifter anyway. I would end up with a floating shell collection. Maybe if I were in a really calm area where there was nothing but sandy bottom, I might try one. Sandman has a good point also about carrying things to the beach from the car. If your walk is not a long one, that could help but my walks to the beach are about 1/8th of a mile from the parking area and I try not to carry too much stuff. I had a moron try to steal my equipment in broad daylight from the beach last year so I started only taking my detector and scoop to the water. When I take a break, I go to my car and take the break where I can sit, listen to music and leave the beach for a little while. I can change coils, headphones, etc., during that time if I need to make an adjustment then go back to the water.
Again, I know that some folks love the floating sifter. I just prefer not to use one.
Good luck!
Jim