David & Bill,
Did you guys read the previous blog written by David? The long & short is that if you're willing to be on the pre-bleeding edge you get exclusive access to the Exchange product team, free support, and the ability to help shape the product moving forward. More
so than just talking about what you'd like to see happen on a blog post or in a TechNet forum post.
Additionally, if you're using Office 365 you're already using some of the new/yet-to-be-deployed-to-on-prem features and functionality, anyway.
But you're right - it's not for everyone. There are risks, but honestly, this is a very unique opportunity to make your voice heard and be supported for it.
I'd make a case for it with my upper-management if we weren't in the middle of a number of numerous transitions and consolidations at the moment. Just no time to give it the attention it would absolutely require.