If 3D graphics performance is important to you, then don't get an MBA just yet, stick with an MBP. I've got a 2010 MBP, my biz partner has an 2011 MBA: for general CPU burning it's on a part with mine; disk I/O it obviously tears mine up. With an external screen it's pretty nice as a development machine, but personally I like the 15" high-res MBP screen too much to downgrade to an MBA.