We've rented before. Our first experience was through David's DVC - we sent over a deposit and inquiry to them, they were very fast to respond but unfortunately did not have the points to accommodate what we were looking for. They put us on a wait list for when the 7 month mark hit which is when point availability opens up to all resorts rather than just home resorts. Me being impatient, I ended up finding an owner on the rental board here and went with them, also very seamless and $1 per point cheaper. So I'd recommend either route.
It is safe and reliable, definitely with a broker or an owner with reviews if you rent on your own. Things to keep in mind are that you cannot cancel or change your dates once you book, and you need to book as early as possible to secure your dates and the room type you want - 11 months out is the earliest you can book if you can find an owner who owns at the resort you want. As mentioned, at the 7 month mark, availability opens up to any resort but the popular dates/resorts/room types may be sold out at that point since those with home resort advantage tend to act well before then. We booked AKV (a large and usually easy to get DVC resort) at 9 months out with an AKV owner, and couldn't get our first room choice. It's also easier to get what you want with shorter stays, split stays, or if you're willing to change room types. Finding enough points for 7+ nights in one room type at one resort can be tricky sometimes.
You should also know that DVC busy times are NOT the same as WDW busy times - first week of December is the busiest time for DVC, which doesn't really jive with the general overall WDW busy times. It's also very hard to get a resort in the Epcot area during F&W.