Investing in Atlas is making a heavy investment in technology solely provided by yourselves: Obj-J and Cappuccino. The foundation being open source may alleviate some concern there, but to do so, the open source foundation will need to be of sufficient quality and usefulness that we feel we can work without your IDE in the future.
I'm also VERY surprised that you're charging for an expiring beta. Doing so will greatly limit user exposure, and I'm pretty uncomfortable with paying for the privilege of testing your software.
You're not Apple -- developers don't need to pay for the ability to test/update their software for an upcoming OS release.