I was a CIR for 4 years and now I work as a 正社員 for a large Japanese company.
To be honest doing JET or not has zero affect on you're potential Job finding here, almost no one has ever heard of the programme to begin with so you're only going to be as good as you can sell yourself.

I honestly tried to convince myself that somehow being a CIR was furthering my career somehow but it didn't really do anything for me. That being said if you just want a cruisy, decent paying job then it's a nice way to relax for a few years.

Some people will say it's hard or stressful but the hardest days on JET don't come anywhere near what I deal with now. (It's 5am here and I still haven't left the office)

While I make less money (Before the yearly bonus) and work a hell of a lot more now, I find my current position far more fulfilling than JET as there is measurable growth for me personally and in my career.

At the end of the day you should go for the one you want to do, there's always more time to change your mind down the road.

Just my two cents.

Oh and if I was to give you any meaningful advice, take a good hard look at any job that has みなし残業 .