Let me preface this by saying YMMV.
With that being said. I always use the Best Buy plan for big ticket purchases.
This is what happened to me:
I bought a 50" plasma TV from best buy in 2006. It was a floor model, the last they had, so I went ahead and bought it. It was going for approx $2500 at the time.
I bought the protection plan because it clearly stipulates if anything happens, and it can't be repaired, they will give you a similar or current model if still available.
Right before my warranty was about to expire the plasma TV blew up (made a loud pop then shut off) while my wife was watching it. This was almost 4 years later...
Long story short. Someone came to pick it up (they outsource local shops to repair items). They told me that it wasn't worth repairing.
I went to Best Buy and told them what the shop said. At first they were going to give me my current TV and that was it. The Samsung plasma TV was about $1100 at this time. Much cheaper than what I paid for originally.
I was very courteous and kind to the person helping me. I decided to speak to the manager - just for ish and giggles. Built a rapport with the manager and was very friendly. I hinted, subtly, that it didn't sit right with me that I'm getting a cheaper model...
The manager ended up giving me a credit for the full original purchase price! Credit in the amount of $2498.00!
I ended up buying the TV, a LED backlit monitor, a few PS3 games, and a Nikon 90D for the wife.
Best Buy gained a customer for life that day.
I made it a point to praise Best Buy whenever I see someone post BB protection plan is garbage.