Quote Originally Posted by Throbert McGee View Post
I mean, to my English-speaking mind, it would seem more natural to use стоит in cases where one has a CHOICE whether to pay money or not.
E.g., "когда не стоит покупать страховку?" ("When is it not worth[while] buying insurance?") -- but when I see the phrase "оплатить налог," I automatically think НАДО! It is not merely "advisable" or "a good idea," but "mandatory," right?
Right. That «сто́ит» sounds too delicate for me too. I’d use «необходимо» or «следует» instead. IMHO.

Quote Originally Posted by Throbert McGee View Post
Hmmm... can some носитель русского explain how the meaning would change if we replace the first стоит with есть (or simply drop it and use no verb)
Nothing would change. «Стои́т» here sounds very natural, but other variants are OK too.