1.9 has held my 220+ self plus 10+ pounds of gear just fine. I am currently using a nylon taffeta that is a lot thinner than 1.9 ripstop.
Having said that. Something that has held once or even a few times may not hold up for the long term. That is why I am making one out of 1.9 oz for my thru. I do not want to test my hammock to failure. I also hang from places I really do not want to fall from.
Is that too much to ask? Girls with frikkin' lasers on their heads?
The hanger formly known as "hammock engineer".