Q: it's a very specific sound that's amazing to listen to and I don't remember hearing it in many of you're previous songs , correct me if I'm wrong tho. 
A: i use it all the time. it's really not that far off from D/E, or E9sus4. which i'd use in the key of A. i also use them in more 'orphaned' key contexts. it's a nice way to land in a new key on that chord as if it's the 5. happens a lot near the end of bridges, if we've launched around through some keys, it's a good landing point for a 5 chord in a new key (or even, back to the original key, if it works out that way.) But it also is just a good textural modal vamp, in which case it would feel more like a 1 chord in mixolydian