Upgrade testing on test site instead of upgrade site

Summary:

Does anyone have experience testing their upgrades on a test site instead of the upgrade site?

Anything we should watch out for or potential issues with doing that?

Content:

We are considering using an upgraded version of one of our test sites (tst) to do testing for upgrades instead of using the upgrade site. The reason is that we have several integrations and these are already connected to the test site. Having to repoint them to the upgrade site and then back to test is quite time consuming.

Does anyone have experience with doing upgrade testing on a test site? Is there anything we should be aware of?