[NOTE] - see our blog post on how to work around a couple of bugs in macOS High Sierra that cause Insteon PowerLinc and RFXCOM devices from working on some systems.
[WARNING] - see this post below for potential crippling issues with High Sierra (though there may be a workaround).
Rather than post, AGAIN, a repeat of what we always say, I'm just going to link to the Sierra post.
Short version: don't do it unless you have no choice. Wait at least a couple of bug fix releases (unfortunately, it appears that all releases through10.13.6 still have the bug). Indigo, for most people, is mission critical and upgrading a mission critical computer to a brand new major release is just not wise. We have done testing and haven't found anything, but our testing doesn't cover every conceivable configuration (it's not possible). We'll fix any issues that are identified (assuming there is a fix), but it may not be very fast. Because the operation of some of your devices will depend on drivers from Apple or other 3rd parties, there may be some things that we just can't fix.
We will post follow-ons on this topic as we hear of issues.