Depends on your method of doing things, how you value your time, and how much you enjoy the process. I do things in batches, so although I'm not nearly as prolific a reloader as someone on a Dillon 650 but I also don't care. Most of the stages will also allow me to auto pilot through them because I'm only powder handling in one of my sittings. I'll generally get home from the range and deprime and then tumble all of my brass (rifle and pistol) and then leave it to dry. Next sitting I'll do all my resizing and then when I feel like it I'll prime it all. I use a hand primer, and that lets me do it in front of the TV, on downtime at work, etc. Obviously those aren't options if I use a progressive. Next time around I'll do powder and bullets. Measuring out powder is by far the most time consuming part of the process, but I'm also doing it with the old scoop and scale method (I have a Chargemaster on order). There's no question that I'd do a ton more in the same time on a progressive, but I'd also have to be more attentive due to the demands of a progressive.
I personally am considering taking the plunge on a Dillon progressive, BUT I have no intention of getting rid of my single stage. I don't shoot my bolt guns in high volume, so I don't have nay interest in reloading for them in that method. Pistols on the other hand..... Let's just say I really like shooting .45, and although I don't have any reservations with my current processes it would be nice to cut the time for reloading 4-500 rounds. In my humble opinion, if you're planning to reload pistol and rifle I'd buy a single stage, figure out what's up and then add a progressive down the line. However if you truly just want to load volume, get a progressive and have at 'er. I have a friend who had never reloaded anything as of this summer (doesn't even own a reloading manual) Got a Dillion 650 in August or September and has cranked out 20k+ rounds of 9mm since with no issues. If you can read, and have YouTube, you can use a progressive without killing yourself, injuring anyone, or blowing anything up.