It is important to distinguish between the Chameleon Toolkit and the Chameleon VMD Editor. The Chameleon VMD Editor is still an important product as this is used for a variety of parsing functions within Iguana. This VMD editor is still regularly updated and these updates are included when you upgrade to a new Iguana version.
The Chameleon toolkit on the other hand is legacy software and is no longer a recommended product. No new features have been added throughout the later versions of Iguana. Therefore, it is strongly recommended not to use it for functions such as networking and development etc.
If you are using the Chameleon toolkit as an API, do not upgrade past Chameleon 5.6.2. The reason for this is is that the networking API and other features have been disabled after 5.6.2.