I would like to ask if you could give me a summary of how this is implemented in .83, as my testing was inconclusive. Thanks very much in advance!

In essence, the heightmap that you see will not be updated until it has come in LOS. So, when someone is teching and blows the com, the enemy cannot see where the crater is.

Unfortunately there are still many ways to reveal the actual synced heightmap, so consider it an alpha feature. Kloot implemented most of the UHM and knows more details.