We have rented points twice and had no problems at all.
We used what is called on these boards as Davids but it is actually called DVCrequest
https://www.dvcrequest.com/
I must admit, the first time I was a little nervous just because we had never done it before but it works out amazing.
We went last summer. I had reserved a package through Disney as my backup because you can cancel within a certain time period without penalty. There were some great room discount rates and even a resort credit that was offered which made it very competitive to purchase direct from Disney( it was still more but not much and I kind of wanted the two hotel room queen beds vs the 1 bed and pullout in a studio). Once we factored in the cost of parking the car over the time we were there it ended up being a much better deal to rent points. As you said in your original post, the parking is included for guests renting DVC)
There is some risk involved though. Davids works as a middle man. You tell them when you want to go and what type of room category. They find a DVC owner who wants to rent out their points. Davids then matches you up BUT ultimately you are renting from the person who owns the points, not Davids. If this person defaults to DVC on their dues or payments, you could be out a room. But I know that Davids screens the people they deal with and they have many clients who have rented out their points before.
There is an area of the Disboards where people do one on one renting and it is usually a bit cheaper than Davids-I have never done that so someone else might be able to comment on that