We have used a 2 liter pot for dozens of days of "one pot meals for two" in the backcountry. By extension, use a 3 liter pot for 3 people.
Those stainless steel pots are great because they clean up well. However, they are heavy and steel does not conduct heat nearly as well as aluminum. That means food burned to the bottom of the pot near where the flame hits the bottom. Home cookware often has a copper or aluminum disc bonded to the bottom of the pot to distribute the heat. Especially on a big stock pot or a frying pan.
My lightweight favorite is a non-stick coated aluminum pot and lid. It cleans up fine if you soak it in warm sudsy water for ten minutes or so. I once got too aggressive scraping it with a plastic spoon and scraped off a bit of the coating. Titanium is worse at heat distribution than aluminum and/or steel. It is barely less weight than aluminum and a lot more expensive. We don't use a frying pan.
This $50 cookset has a 4 liter pot, a 3 liter pot, and a lid. I would expect the 3 lter pot and lid would weigh a bit less than a pound.
http://www.rei.com/product/636949
The trend in "ultralight backpacking" is for alcohol stoves instead of white gas stoves. These setups weigh about 12 ounces less than my MSR Whisperlite stove setup. Google "ultralight backpacking" . They do a lot of tricks with the windscreen for efficiency.