Nickmoore

I just purchased a 2007 SL55 with 31,000 miles on it. I took it to my local MB dealer and had them check it out. I also have the VMI record on the car. It was very well maintained. I am considering an extended service agreement .... Lexus Platinum or Nissan Quality Guard + Plus Supreme. In honesty I am not a fan of extended warranties/service agreement. I would appreciate information/advice/opinions on 1. Should I purchase an extended service agreement? 2. If so which one. 3. Is the dealer the best/only place to buy one? I am new here and really not sure how to post/tag this. Thanks.