I can't tell you what to do, but I'll share my David's experience with you:
We have used David's probably 7 or 8 times now. They have wonderful & responsive customer service and a chat feature on their website that is actually staffed by a real, live person that works directly for David's!! We have never had a single issue with renting points from them or attaching the reservation to our My Disney account, nor have we ever had a problem checking in or getting what we rented.
You may be aware of how it works - but in case you are not, this is it in a nutshell. You choose your dates & what type of room & where you want and submit that from the website submission page along with a small deposit. I think it's $99 but I could be wrong there. They'll let you know if they can accommodate your request. If so they will require payment in full, minus your deposit. If they can not accommodate your request they may offer you either slightly different date or different room type if available. You'll be able to say yes or no. If you say no you get your deposit back. You also get your deposit back if they are unable to fulfill your request. On the submission form you also have the option of picking a secondary/back up resort. At least that is how it was last time we used them.
I think there may be a third party insurance you can purchase but I have no info on that as I have never used this.
It is non refundable (outside of any insurance you may buy) and a use it or lose it type of situation.
I'll actually be contacting them later this week to submit a new request to rent point for next year.
I think it's a great deal for staying at the Deluxe resorts for a lower price. It may not be a ideal situation for people who need to have more flexibility in their plans and/or can not absorb the cost of the rental if they can't make it - but it's worked for us. Of course, we have a fair bit of flexibility w/ our jobs and we have no small children so it's easier for us.
Have a good time on your trip. We've done Wilderness, Boardwalk, Beach Club, Animal Kingdom, Bay Lake Tower, Old Key West & Saratoga on point rentals so far...working our way thru the DVC properties!!