I have used braided mason line for tie-outs on a tarp, even had them configured as whoopie slings. No problems at all. Worked well. In fact, the whoopies seemed to work very well with the mason line as the friction seemed better than say amsteel.
I am still using mason line for the tie-outs, but i don't use them as whoopies anymore. Instead, i just put a marlin-spike hitch with the stake before I put it in the ground. Easier, faster, and more flexible in my opinion.