Is upgrading Version 6.8 ( Perpetual Licence ) to Version 6.9 Worthwhile given I don't have one of the newly supported cameras. That said are there any risks / new bugs etc in the Upgrade ?
I think you will find it is generally recommended to install all updates. But the choice is yours. the only problem that I know of that still exists is the side panels still sometimes go blank on the Mac operating system.. Adobe is still working on solving that issue.
A lot of known issues were fixed in the latest update release. See the list here Lightroom CC 2015.9 now available
We recommend you to keep the product updated to the most recent release. Let us know if you come across any issues.