Hi
It is quite a difficult question you ask here. But yes there is a likely chance you can hit signalling and media flow issues (without being able to tell you exactly what and how as it is scenario dependent).
In terms of security we recommend the latest software version available for our TelePresence systems. TC5 is, as you already seem to know, no longer being maintained.
This is a very old software release so doing a comparison between the new software releases and old going back several years is not a task I want to take on :). There are hundreds of bugfixes between TC5 and TC7. I can only recommend that you read through the release notes of TC5, TC6 and TC7 to get a better understanding of what has changed the past years of development.
If you are happy with staying on TC5 and you do not encounter any issues with your current deployment, no one will force you to upgrade, but in a support scenario you might hit a brick wall until the system is upgraded.
Staying up to date would also provide you with new features so you can make the most out of your TelePresence equipment.
I´m sorry if I was not able to provide you with a satisfactory answer to this post.
/Magnus
