I do, mostly for my dove and quail loads in 20 gauge. I have a 12 gauge MEC that i've never used, but if I ever actually get back into duck hunting like I say I am, I'll definitely be using it to load for that application.
My caveat is that I got both of my presses for free and to be honest I've only bought powder, primers and a bag of shot because I was gifted a lot of components. So for me, right now, it makes sense.
I can also load a box of shells in about 10 minutes. Almost no time at all. The great thing about shotshell loading is that once you get your components squared away, there is no measuring, no fussing - just loading. Considering where I live that it takes me at least a half hour to get to the nearest Academy or BPS to buy shells, I can load a case of shells up in about the same amount of time it would take me to go buy a flat. And I don't have to burn gas or interact with people.
I'd agree with most others though - if you are trying to compete with you run of the mill dove or clay loads at home, you'll likely not have a lot of success on the financial front in 12 or 20 gauge. If you are loading something different or loading gauges or bores that are just hard to find, then you are ahead of the game.
I like it for my 20 gauge because I can load shot that I typically don't find in the store (#6 7/8 oz shot), which is what I prefer to hunt dove with over the more common 7-1/2 shot.