Since the GNS530/430 has the option to show weather and lightening strikes, is this something that can be added to these units? Similar to the overlay suggestion for the GTN units?

Hi, isn't this the stormscope device?

Reminds me we've implemented a working stormscope device in our SN3308! This would be a cool addition, but I certainly wouldn't consider an 'overlay' a good implementation, rather have it in-device as-if a real stormscope device was connected, with all the GTN on-screen controls available and in order!