When you leave Private Beta, you will only lose the following elements of your site:
- The old reputation tiers will be shifted over to the graduated site tiers. Which are much steeper than the Beta phase.
- You will lose the "Sketchy" theme in favor of the new theme that Jin will design for you.
- You will lose the "Site Stats" and "Help Us Grow This Site" banners on the right sidebar of the homepage and similar pages. These will be replaced by your normal adspace, which will rotate between new Area 51 proposals, interesting questions on the network, and community ads posted here on your Meta. This is because the Site Stats and Growth banners are intended solely for the promotion during beta.
Everything else - all functionality and mechanical systems, will remain the same. There is no true "loss" of features in graduation - it's something you should be looking forward to, after all. ♪