Keith,
Depends entirely on what you're doing. I have, and use progressives on a pretty regular basis. While I use single stage presses for much of my reloading, it's usually on those cartridges where I'm loading a very small quantity, or need to weigh charges, such as my Long Range ammunition. For shorter range stuff (or any other ammo where I don't need weighed charges), such as my 200 and 300 yard loads, the progressives are just fine. The difference is in part the fact that when I load this Short Range ammo, I'm loading at least (bare minimum) 1,000 rounds at a whack. I'll often do considerably more than this, depending on the shooting scheduled I'm looking at. Prairie dog, plinking or varmint ammo, progessives, all the way.
For pistols, again, it's a quantity issue. I'll very rarely load less that 1,000 rounds at a sitting, and generally won't even change over the press until I know I'm going to be loading 5,000 rounds or more. Much easier on a RL550 or RL650, but the 1050s take at least 30-45 minutes to change over, so I wait until teh quantity to be loaded justifies the change-over time.
If the presses are set up properly, you can load ammo on a good progressive that's fully competitive with anything loaded on a single stage. Proven that to my own satisfaction, and have no hesitation in using these for even the most demanding match ammo.