Posted 25 June 2016 - 06:05 PM
The other potential reason to upgrade is that Apple no longer "supports" Snow Leopard (aka Mac OS X 10.6.8). This means they no longer patch bugs or provide security updates. Since you use this machine for email and browsing, there is a chance (albeit small at this time, but potentially getting bigger) the lack of security updates might be an issue.
Personally, I would likely update to at least 10.8.x. It should have no problem running on that iMac (I have a MacBook Pro of around that time frame that is/was running at least Mac OS X 10.8.x with no issues...it is currently not working...not related to the Mac OS...just won't boot...suspect it might be a battery issue...if I get it working again, I will likely upgrade the OS).
FWIW, if you are not really sure, then you can first clone your current setup (using either Superduper or Carbon Copy Cloner) to an external drive and then upgrade. If you decide you don't like the upgrade or have problems, then you can use the clone to revert to your current setup (i.e. boot up the Mac using the external drive and then clone it back to the internal drive). Personally, I do this by default for EVERY major upgrade of the Mac OS (and also for my Windows machine) and generally before even minor routine Mac OS updates...and before updating/upgrading programs or install new programs. It gives me a good fall back position is there is a problem. Plus it is a bootable back up of my system that will be current at least as of the last time I ran the clone...speaking of which, I need to update my clone of this computer and do some updates (I generally wait to let other people be the Apple (or Microsoft for my Windows installs) "test dummies" for updates/upgrades). If you do this, if/when you decide that the new version is fine, then you can update the clone so that it would become a backup option like what I do.