I have one of these - I use it for 10G batches and it works just fine. Slow - definitely, but it works. Plus I can take it from my garage, and throw it in my trailer and use for camping on the weekends. It is a rockstar for camping, and I think it suits me fine for brewing. It holds two kettles (one full of water, and one full of wort) no problem and I even put it on a Coscto lifetime plastic table and the table holds all of this no problem. Then makes gravity transfer of strike and sparge water a breeze!
I just add hot water from my washer tap, and it takes about 30 minutes to get up to 180 F for strike water. During that time I grind my grain, and prep the other parts of the brew day.
Then once I've mashed, and collected the wort, it takes that and gets the wort boiling in roughly the same time. That gives me time to clean/sanitize/warsh/record/drink.
I give this three thumbs up, but I have to say that I already owned one of these when I got into brewing. I have been considering an upgrade to a blichmann floor-standing burner or even the 60,000 BTU camp chef stand-alone burner.
I vote yes because of the multiple purpose use! I even have used this for home pressure-canning.