If you're willing to deal with the development overhead of creating/storing multiple formats, which if you super care about optimized content serving you're doi

If you're willing to deal with the development overhead of creating/storing multiple formats, which if you super care about optimized content serving you're doing anyway for sizes, then just use a picture element with fallback sources. Progressive enhancement applies to more than just JS, and we've already been provided with a standard way to not have to care about browser support.