Should I choose the limited (flex) or unlimited option offered by clear correct? $500 dollar difference.

3mm of crowning in one bottom teeth. not sure if I want to pay extra for unlimited because I am a very compliant patient. The unlimited includes free retainers for 5 years while I have to pay for extra retainers with the limited option. Is this a good value? Do CC deliver the result as their 3D model shows without revision? What if there is issues that is not caused by the patient (like aligners don't fit), do I still have to pay to get it fixed? Any advice would be helpful, thanks!