Hi - will the Enterprise version of Experience Builder ever be available as a separate install from the main components? I'm frustrated with wanting to build a full experience in 10.8.1 but I notice that a lot of the things I want to try are only available in the AGO version (even simple stuff like the window option for a splash screen). Is there any plan to ship it separately from the rest of Enterprise so that users can take advantage of updates throughout the year? I remember Insights being done like this when it first came out. It would be a HUGE help.
Take a look at the developer edition of Experience Builder. Its updates lag a bit behind AGOL as well, but it updates independently from Portal, so you can take advantage of newly-added features, such as the window splash you mention. EB Developer is at 1.3 right now, so it's a few steps ahead of what you have in the built-in Portal version.
It does not override the built-in version. The developer version of Experience Builder (similar to Web App Builder - Dev), is installed and run separately.
Once you've finished building your "experience", you publish it, which loads all of the necessary components into a zip file. Then you just unzip that file into a directory on your web hosting server. Or really any web hosting server! You can see the deployment page for more details.
For example, here's an experience I published: https://maps.co.kendall.il.us/betaviewer/
The files are on my web adaptor machine, in the folder .../inetpub/wwwroot/betaviewer. That's another key benefit of using the developer editions of the app building tools -- nice URLs!
Once it's published to your web server, you can continue to work with the local experience without affecting the web version, which makes it easier to test out new ideas before deploying them to your public-facing pages.