I've used one for about 4 years, mine works great with all powders, including W231 and Power Pistol and Unique. But I had to work and fiddle with it to make it flawless.
You can make it work down to about 3 grains of most powders if you understand that 'bridging' is not the problem with this adjustable disk. The problem is keeping the cavity directly below the hole in the hopper. That's why some guys say it works for large charges, but not small ones. When set for large charges, it always puts the cavity directly below the hopper port and it fills the cavity fully. But adjusting it down very small moves the cavity forward until it's not below the hopper port any more, so it fills the cavity unreliably. Take it apart, work with it until you can get a small cavity below the port and it works great.
That's the problem with some of the equipment in the Lee line. It works, but only if you know how to fiddle with it until you correct all the bugs. Once corrected, the machines load tons of ammo as well as any other. But finding all the bugs and tweaking the corrections is like chewing on a leather tit.
Leakage: Adjustable disk leaks badly with the old (obsolete) Auto Disk. The new Pro Auto Disk with the teflon seal leaks no more than any other powder measure on a progressive or turret, unless you have it assembled incorrectly. Incorrect assembly leaks every time. Correct assembly with the teflon seal, and it leaks a total of 5 to 10 granules onto the shellplate during a run of 100 rounds. That's about the same as my Dillon with the same powders, it's good but not perfect.