@jws Oh no, I have Spotify (and am experimenting with Google Play Music for a while) and so all Siri does for me is find the song. Shazam's experience was a bit jarring when the idea was to find the app, start it, wait for the loading time, wait for the network, hit the button. It's gotten better now, with or without Siri.
But you're locked into your setup. Not trying to sway you :)