If it’s only going to be flood-filled with a colour, I wouldn’t bother. If you needed to put text or an image on the curved part of the UV template, you’d either have to straighten the lines, or curve the text to match, as you can see from the distorted text on the bottle-top.
BTW, I’d rotate the UV island so as to be perpendicular to make straightening the lines and placing the text easier:)
PS - you can make life easier for yourself by UV mapping before smoothing - easier to select seams:)
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