I dilute with a bit of water. My espresso comes out delicious but concentrated so I add a splash from my glass. Opens it up and brings the temp down to where I can immediately begin drinking.
Not a direct answer, but a long black is typically less water than an Americano. It's usually a bit more than a splash of water, though. I enjoy them for all the same reasons--good temperature right from the start and more to drink for a longer coffee break.