We are planning a 1 to 1 rollout for our students. We will be using Office 365 for staff and students and currently are reviewing devices. We are fairly sure that we will be using different devices for both groups, as we are looking to have more robust (read connectors) for staff, and a lighter, less-expensive, option for students. We are also looking into ownership options for students, as we feel that students would treat the devices better if they owned them.
We have tested the Lenovo Flip, Nexus 10, Surface RT and Pro (originals), Unobook (CDI), and Lenovo X131e. I am waiting to test the new Surface 2's and the Lenovo Yoga.
The Flip is a very good hybrid device. The cost is high (most tablet prices are going higher!) at $1100, and the hinge mechanism appears too fragile for student use. All in all, it would make a good device for teachers.
The Nexus 10 (without keyboard) is a great android tablet if your looking to go with Google apps. Battery life is good. I haven't tried it with a keyboard yet.
We didn't like to original Surfaces, though I understand the new ones, with Windows 8.1 are much better.
We are going to order the Lenovo Yogo now that they've been released.
thanks
marc