I palace fronted into an IMA position from AD as on O-4 and I find myself in a similar situation... I never did ACSC/IDE and I am meeting my first mandatory O-5 promotion board at 7 years TIG. I have 16.5 years of total service.
I realize there is a risk of not getting selective continuation if I am passed over twice, and that I may get a mandatory separation date, rather than the opportunity to continue until I am retirement eligible at 20 years of service. (Results will come out in a few months, but assuming I get passed over)
I did opt into BRS before I separated Active Duty, since I originally thought I was going to cut all ties back then, and now I do have a job with a major airline on second year pay. I am wondering now, is it worth it for me to crank out ACSC before I meet the second O-5 board? Or bigger picture, is it worth it for me to still actively pursue a reserve retirement since I am in the BRS and now have my airline job?
Another reason I have not been motivated to do IDE and promote is that my current IMA position is only authorized a maximum grade of O-4 (unit has requested to make it O-5 but has been denied), and I really enjoy the unit and location of the job. I would not be motivated to work in a different reserve position, and I could more than likely be better off and enjoy better quality of life without a reserve job.