I am going three years and four months long on a twelve year old automobile that is a daily driver coated with Opti-Lens. I detail my vehicles regularly, but living in Southern California with drought conditions led me to letting this automobile go up to six months without washes (it is stored in the garage during the night). During the day it is a commuting road warrior. I can state, without question, that Opti-Lens is a superior coating as the headlights still look like new! This starting from a situation that you mentioned—factory peeling, and I do mean bad peeling and hazing.
3M makes an excellent inexpensive headlight restoration kit that is easily available at your bigger chain stores. I used the kit with my Griot's Garage small orbital versus the drill attachment in the kit. I did spend several hours sanding and prepping as this step is imperative. Coating application is super simple and my advice is to prep and coat all your other lens on your vehicle(s) at the same time.
Would I recommend Opti-Lens? Highly!!! If cost is a factor simply get some friends or family members to pitch in and do their lens too.