During a foul-weather test run in the back yard, I did notice a downside to the mason's line--it's very supple and offers almost no resistance. No biggie when the fingers are doing what you tell them to, but it becomes an issue in cold, wet conditions when finger dexterity is more difficult. I still take it over the paracord, but dla's suggested use of 250lb test Spectra fishing line (included below) is probably much easier to work with, and also avoids some of the stretch issues that come with nylon.
Bottom line: If you've got $44 to spend on 150 yards of Spectra, I would definitely look into it (you do get way more bang for the buck than trip-tease); however, if necessity dictates that you've got to keep it on the cheap (under $10), the mason's line does a serviceable job, and Home Depots are fairly easy to find.
You're gonna need a bigger hammock