First a correction - Company is no longer part of Luna. They are part of OSI Optoelectronics since 2018. Worked there full time 22 years, part time later. Great small-company work environment. No politics. Many of the employees have been there 20 years or more indicating company stability and worker satisfaction.
Inconvénients
Being a small company in what is not really a growth industry there can be somewhat limited opportunities for advancement. Four day work week (long days) may be a pro or may be a con depending on your preferences.