I think it is a reasonable deal for those that want to upgrade considering that a new top has to be provided.
For me, I am not sure I really see enough pros to justify the upgrade. If I ever sell my current #3, I would get the #3D, but I put out some pretty darn good food without the Auber, so think I will hold off on any upgrades to the short term anyhow. I will be interested to see some videos/instructions of how tough the upgrade is though.
To each his own on whether to go standalone verses the built-in option. For me, it I was going to get an Auber, it would be the built-in option.