You know only you can answer that question as it involves a very personal bit of info: Your Disposable income.

J and F, when the customer is paying and not the employer, are for those who can happily take the premium without it hurting. As others have pointed out you get much more bang for your buck out of nice dinners and good hotel rooms.

As some one who has tasted the sweet comfort (through upgrades and once, on LH a true opup) of C/J when I am relegated to the back I tell my self I am earning money (or miles by not dropping them on an upgrade) to be spent elsewhere.. Single income earner (Thanks USA immigration system) with kids and a mortgage, I am a posterchild for Y

Another issue of stretching the budget to fly in a premium cabin is that it will raise your expectation. Bad service and issues will seem to be exacerbated.