It really boosts the clarity and reduces output at the same time. Of course lowering the pickup by itself will reduce the output, gaining a bit of clarity on a humbucker, but raising the pole pieces really unbalances the coils, so you get infinitesimally closer to something like a single coil, but maintaining the hum cancelling. I actually ended up also slightly lowering screws in the bridge too, for the opposite effect! For me though, I found that even in its extreme setting, with the bucker way down low and the pole pieces insanely high, nothing beat the sound of it split, so I actually have a 10K Artec noiseless single coil that should be delivered to me today! With that, I'll have an HS setup, which should work great for my purposes. But for those who really love a humbucker in the neck, I do think unbalancing the coils is the best, because you really start to get more a holy grail PAF tone then, just very very sweet and soulful, at least in my experience.
This is with the big caveat that it's very dependent on your pickups. I also have a set of Duncan Saturday Night Specials, and with those I don't think you need to adjust anything in a hardtail guitar. I had them in my Washburn Trevor Rabin, and they had the most nuanced, incredible, and incredibly balanced response, just perfect for dynamic playing. They worked great for me, as someone who's insane about riding the volume and tone knobs constantly.
But my current guitar demands way higher output not to sound harsh, so my current pickups sound great, and for fantastic Les Paul tones, I've found that lowering the bridge pole pieces a tad, raising that pickup, and raising the neck pole pieces a ton and lowering it just made my current superstrat essentially feel like a Les Paul.
And apparently an old trick for Les Pauls is to set your tone to the neck pickup with the volume and tone knobs at 10, then to roll back the tone knob on the bridge to balance; this was mentioned in some YouTube video I saw a while ago. I find I just like to set my HH tones to the bridge with the tone knob at around 5 and the volume back around 8.5 - 9, then I have a much fuller range to play with when actually playing.