I always rent points from a broker and I will continue to do so.
However, they do say that 99% of the time there won’t be any issues. Well, I was one of the 1%. I had booked a studio villa at the Poly at exactly 11 months out for our Sept 2019 trip. In May of 2019, I got an email that the person who booked our trip (whose points we rented) didn’t pay their dues and Disney cancelled the room. The broker tried to book us another villa but they were sold out at the Poly as well as anywhere else we would want to stay except for Old Key West and Saratoga Springs. They were willing to upgrade me to a one bedroom at Saratoga Springs as that would be “equivalent” to the Poly in terms of cost (and what the contract promised), but it wasn’t equivalent to me in terms of location and hotel level.
I ended up getting a refund and eventually booked the Dolphin saving $900 from the original reservation. I do love the Dolphin so I was relatively ok after the initially shock but we were traveling for my son’s 13th birthday and his only request was staying at the Poly so he was really disappointed for quite awhile.
I have another villa booked in February 2020 (I booked it before our Poly trip fell through), so I am now watching the reservation like a hawk to make sure we don’t have any issues! Worse, we are traveling with my in-laws who have never been and I convinced them to rent points telling them that it was perfectly safe.
I haven’t told them about my May experience... hoping they never have to find out!