You pretty much answered your question with your first statement. X-Plane is constantly changing (usually for the better!). You purchased the Beta version, which is pretty much a taste; a sampler of what is to come. (Soon, we all hope)! Even when XP 11 goes final, it will still continue to grow through future revisions.
If you purchased XP11 after mid-September of 2016, you should be able to download XP10 for free. I'm not sure how that works, but you can find more info on the following site. XP10 is very stable, and you can download additional scenery packages from this site:
http://forums.x-plane.org/index.php?app=downloads
When you downloaded XP11, did you pick which scenery you wanted and download it also? You have the options of picking what areas of the world you want, depending on where you like to fly and your storage capabilities.
Here is the link to the X-Plane Knowledgebase. You can find the answers to almost everything there. I hope this helps.