Over the years on Connect, I have seen questions around upgrading and whether or not this is a viable option, and have given enough advice around specific requirements for, and against upgrading.
This is either met with instant acceptance, and a lot of further questions of where to get the latest version, how to go about it, pitfalls that can be experienced etc. However, quite surprisingly (or is it?), some OPs state they either have no intention of upgrading anytime soon, or state outright that will never be an option.
So which is the right choice? Well, neither, but here are compelling arguments for both sides...
To Upgrade...
New software is released constantly, bringing with it new enhancements, patches, tweaks and the like. Software vendors need to keep track with this, and in turn, release either new versions which are either totally new, or simply incremental improvements which patch their software with hotfixes, or service packs.
Along with this, software vendors, like Microsoft, would retire software from active support, leading other vendors to eventually stop supporting those packages as well. This places companies in a predicament...do we NOT upgrade, and stay behind in the tech race, or take the plunge and upgrade...sometimes at quite a cost, as it would mean a hardware refresh too. An example of this is what happened when Microsoft finally retired Windows XP forcing companies and users into migrating to at least Windows 7 in order to receive security patches and updates. Most PCs running Windows XP would not have been able to run Windows 7, leading to hardware purchases to compensate for this.
In this case, upgrading makes sense. If your company has the budget, it places you in line with numerous other companies (sometimes your direct competitors too!) who have brought IT environments up to standard.
Technology and software is moving along at a very fast pace at the moment, and some companies are still far behind in this race. I know of companies still running Windows Server 2008 R2 for instance, where Server 2016 has been out for well over 18 months now. But, companies like Symantec are also releasing new versions of software with vastly superior capabilities being included which address new functionality in software, meaning if you want to take advantage of these, and you’re on the bleeding edge of what’s currently available, you’re going to want to upgrade soon after new software is released.
From my side, I generally upgrade a month or 2 after release. This allows me to keep current with what is available, and to make full use of any new functionality. It's also just personal preference...it keeps us ahead of anybody else that we know of who is comfortable not changing their backup software, and allows me to prove to them that having the latest-and-greatest version out is worth the effort of getting it installed.
...NOT to Upgrade...
...if it ain't broke, don't fix. That would be most people's answers to this. They've used older versions of software for so long (some guys are still on old versions of Ghost for instance and only NOW looking at Symantec GSS as thy’re upgraded Server OS’s for instance), and with an environment that either doesn't change, or is unlikely to change for the foreseeable future, there would be no need too.
Cost could play a factor...the budget needed for upgrading infrastructure in terms of servers, storage, new OS licenses etc. would simply be too much for some companies. with no upgrades in sight, there would be no need to upgrade to a newer versions of software.
Some people are lucky enough to never have had an issue with their version of software, and might be logging their first serious query. For this reason, they'd see no reason to upgrade. What has worked in the past, would surely continue working, especially if there isn't much "tinkering" on the software itself.
Lastly, upgrading could be a more long-term process. Many would rather let a particular version settle in...by this I mean they'd play a wait-and-see game...any issues that would crop up on initial release would be fixed with hotfixes, patches, or service pack releases, and once the major issues have been dealt with, they would then consider upgrading.
Which would be the correct choice? Neither...it depends on where you are with your company's technology, and where you want to be in the short- to medium-term. Many will continue to advocate upgrading as a means of fixing issues, or supporting new software/hardware, and this is the line I would take, and suggest personally. When you do so, however, is entirely up to you!