It really depresses me when I go to events or lectures and somebody mentions, usually with a smile, that poetry is what is lost in translation or that to translate is to betray (following that Italian proverb). It shows that translators and translation scholars still have a lot of work ahead in showing people what it is that they do.
The notion of poetry being lost in translation is based on seeing meaning as something that is hidden behind a text, something that the text decodes, whereas, as Wittgenstein said, nothing is hidden. The meaning is in the form, not in some Platonic Form. Therefore if we pay attention to form, we can write a target text that will not clone the source text, which is an impossible expectation, but may well be a work of relevant similarity, to quote Andrew Chesterman. And as the above comment states, there may well be gains.