Just to muddy the waters a bit more, I recently received the
RBTR 12' straps made of UHMWPE and they are 1.79 oz per pair (on my digital scale).
I haven't used them at all yet, not even a test hang, therefore I have no idea how much sag to factor in. RBTR recommends not using buckles of any kind with them, so they will be used in warmer weather with Becket or J-bend into CL.
For info, the weave of this material is pretty tight and there are no gaps visible between the threads if you tug it on the bias.