I've recently stepped up to all-grain brewing, which isn't terribly more complicated than extract brewing. Instead of using a prepared mix of grain extract (either powder or goopy liquid), you simply soak crushed grains in hot water, and then boil the resultant run-off. It takes a little longer to do, and it requires a little more equipment (which further increases the time involved to clean and sanitize), but in theory it allows for a little more precision in the brewing process. When using extract, your beer will be whatever the extract was made to produce. When using all-grain, you can control the temperature of the water applied to the grain to vary the resultant beer, if you so desire.
The other big difference between extract and all-grain brewing is the size of the boil you use. Most extract recipes are geared toward about three gallons of boiling water. At the end of the brew process, you add water to bring the final volume up to five gallons. The recipes all account for this intentional dilution. With all-grain, you generally boil a little more than five gallons of wort, expecting to have some boil-off that will reduce your final volume to five gallons.
Of the handful of all-grain batches I'd previously brewed, I always had boil-over: the water boiled up and spilled over the sides of my brew kettle, creating a big mess. The brew kettles I've used are all just a little over five gallons, so I've never really been able to brew correctly according to the all-grain recipes I've tried. My beers have all been adequate, but the effort and headache involved have been inordinately high.
I've been eyeing a number of larger brew kettles lately. My thinking was that if I were to get, say, a fifteen gallon pot I could do a full ten gallon boil, which is basically the equivalent of two of my normal batches of beer. And I could easily do a full five gallon boil without having to worry about boil-over.
Yesterday I brewed a barleywine all-grain recipe, and I borrowed a friend's twenty gallon pot for the boil. While I was able to avoid boil-over, I found the entire brew session to be much more cumbersome than I expected: a twenty gallon pot is simply too big for a five gallon brew. It was overly heavy and awkward to lift. It took a lot longer to reach a boil on my burner, likely because the surface area on the bottom of the pot greatly exceeded that which could be heated by my burner. My immersion chiller worked less efficiently because less of the coils were submerged in the hot wort, which made my delay pitching the yeast a lot longer than I would have liked.
Reflecting on yesterday's experience, I've decided to scale back my purchase to a ten gallon pot. The reality is that I'm not likely to brew a full ten gallon recipe any time soon. The idea that it's an option available to me is a red herring, and not worth pursuing. Simply being able to avoid boil-overs is sufficient for my brewing experience right now.