Using Lightroom 4 on 11" MBA 8GB 2GHz i7 + TBD

Hello, does anyone have experience with this setup or something close (different config mba)? Will this perform well enough (editing RAW files) or should I look at the 13" MBP instead of the MBA, or should just (wait for and) get the new iMac and a second device (iPad) for mobility?

I've been meaning to upgrade and streamline my equipment, I need a powerful enough computer at home with a big screen for editing photos and mostly web development, while having a mobile computer for when I leave on the weekends that would be used mostly for browsing the internet and uploading photos.