Never had an extended warranty, but have read what others have said about them and I will pass it along as others will also I would guess, especially those that have bought them.
1. The "Devil is in the details". Watch out for the small print.
2. Alternate plan; instead of buying an extended warranty, put money aside for emergencies and unexpected issues. Some say you will be ahead this way. But then again, they may not have owned a Thor kit coach.