Like SD, I use the sinking type a lot. Mostly on my 5,6,7 wt single handed rods and on my lightweight spey rods 5/6 wt. mostly for trout fishing. Its faster to change a leader than an entire line and I can vary the sink rates and lengths at will. Never used the other types.
I also use them when I guide, to help folks who are not used to full sink lines or fast sink tips, it's like having a warm up session with lighter sinking tips before getting into the real fast sink tips or lines and most (inexperienced) clients find it easier to cast with. They handle weighted streamers very well. I mostly use RIO (sponsor).
One trick that I do is to clip off the short mono piece and tie on a loop, then I can also vary my actual leader (mono) lengths and strength.
Pete AKA Frenchcreek from Calgary