Good Day. My first post:
No, if the Nine Kings had known the outcome of these "gifts" they would have surely rejected the Rings. If we have a look at what these Men were initially looking for, we could enumerate might, wealth, prestige, longer life, wider realms, etc. Given that they, for a short time, were able to achieve these results with the help of the rings we have to confront these profane benefits with the price they have to pay for all that.
Losing oneīs physical body, becoming an obedient servant of Sauron (who is indeed not famous for fair rewards), ever yearning for the One, living a restless life that is (similar to gollumīs) more "stretched" than prolonged, fearing the light of Aman in all its embodiments and worst of all not knowing to what end one, as a wraith, will come cannot demonstrate a kingīs wishlist for the next decades. Where do their spirits go after they are defeated? Are they still allowed to leave Arda and lose the burden of being part of it?
The fate of men after their fall is not declared to the Valar, and even the most evil men will surely remember the power of Eru that they are subject to and reflect the deeds, either with shame or pride, before they die.
I guess the light of Aman can be more terrifying than Sauronīs devices of torture when all is over.
Men cannot escape fear, for it is part of both sides, good and evil. Being empowered by Sauronīs Rings does not add to their worthiness of their lives nor to the fulfillment of their human desires. Yet (I love this sentence in the Sil. altough it is not used in this context.) it is for them neither reward nor punishment, but the fulfillment of their own being.
This issue strongly reminds me of Goetheīs Dr. Faustus but this would be too much off-topic.
Anyway, think twice before accept gifts from fair looking strangers
