Yes it can be interchanged. The problem is the case itself, it will crack where the mount slots into it.
Maybe one day I'll get around to take a shot of the typical damage, a friend of mine has some heavily (ab)used D-Lites that have the typical cracks.
The new D-Lite it are a lot better.
Intended useage would be an important consideration for sure. For my use and setting the plastic bodies are fine. If I was making my living with these lights and they were getting knocked around quite a bit I would be investing in something up-amored.