I also attempted this for a while. I could accomplish work (I worked primarily through SSH), but it was always a little forced. Since then I've decided to make the iPad primarily used for its design, i.e., entertainment and my MBP used for its design, i.e., work.

I've found it really helpful to separate the two domains. The separation allows my mind to know which mode to be in and thus allows me to focus when working and relax when relaxing.