Yes, I have one. I use it very occassionally, normaly when I load a small batch of 'my very best' 308. I find it simplifies the specific process you are undertaking.
Is it better than just owning a single press? Unlikley, but I like the ability to just use the one die, for that specific process, to a high degree of accuracy. Going from one stage back to progressive was a bit of pain at first, now it takes a couple minutes and I'm back to mass 9mm production.
I also have limited space, so my one press 'does all' approach is maintained.
Candocad.