I've been a recent convert to water flushing over the past month or two and I like it, I think. A couple of notes:
1. It may be a bit pipe specific, but I do get a bit of gurgle with pipes that smoked dry before I started flushing. A major example is my Peterson Shannon 150. This pipe smoked wet when new, but after a lengthy break in, was quite a dry smoker using the traditional pipe cleaner, no flush cleaning. With the water flush, there are 3 or 4 times per bowl where I have to run a cleaner through, or cover the bowl with my palm, and snap my wrist like a Clayton Kershaw breaking ball to clear it. I tend to smoke these pipes nearly daily so maybe more rest/drying time would alleviate this issue some?
2. It has not really saved me any pipe cleaners. While flushing, I will typically run the water through for about 10 seconds at a time, and then run a pipe cleaner through it, repeating until the cleaner comes out clean. After that, I leave a cleaner in the airway and store until next use. Usually takes about 3 cleaners per cleaning.
3. Time will tell, but my pipes seem much cleaner. So far, I have felt no need to do any deep cleaning on my flushed pipes, even those I smoke every day. It also helps with the exterior of the pipe, the rims of my bowls and silverwork. Like Hoosier mentions in his OP, after the first flush/pipe cleaner, the airway is real clean, and any remaining gunk is from the area where the airway goes into the draught hole and chamber.
4. I have noticed no damage or issues to any of the pipes I flush clean. It has also not made my vulcanite stems any worse in terms of oxidizer ion, which was a concern I had.
So I will keep doing it, and experiment a bit. My main motivation was to greatly reduce the amount of deep cleanings I had to do, because I hate deep cleaning pipes and find it tedious as Hell. So far, it seems like it might be real helpful in that regard.
Just my 2 cents and personal experiences, of course. YMMV