Echo will not accept a 'Set' command for a scene, however. It does allow turn on, off, brighten and dim for scenes. From what I can tell, only an individual dimmer will accept "Set XXX light to 50%".
I have a 4-way switch with three 2477D dimmers, one of which is actually controlling the light. They are combined in a scene, and work correctly - all control the light and the other two dimmers.
If I add the scene to Echo, I can only turn on, turn off, brighten and dim (about 1% a command by the way - pretty useless). If I add one of the dimmers that are NOT physically powering the light, only that dimmer will respond to the command, but the actual dimmer will not. If I only add the dimmer that is powering the light, I can then say 'Set XXX light to 52%" and the light will be set to 52%. The other two dimmers in the scene will not show that setting however - they remain at whatever the scene was set to locally. As soon as I use any of the dimmers in the scene locally, they sync.