I asked the forum how well Logos 4 works on the 11.6" Macbook Air (late 2010) - and I must say it works really well!
I have Scholar's Platinum + a bunch of other resources I've purchased over the last 2 years. I let it index overnight, and this morning it was ready to go. I ran the Passage Guide, Exegetical Guide, and they were fairly snappy. Not much different IMO than my Core i7 27" monster iMac. I think most of my speed issues with Logos has to do with scrolling speeds of the windows. My i7 has a much higher res display and so it has more pixels to scroll - and that seems to take Logos forever. Smaller window sizes seem to refresh much faster.
The screen is very legible, and while I like reading on my iPad better (due to being able to read vertically) - the screen is higher res on the Air.
I have the maxed out 11.6" model - 4GB of RAM, 1.6Ghz CPU, and 128GB SSD. This thing weighs almost nothing - it'll be great when teaching Sunday School, or Bible Studies. Plus it runs Desktop Software unlike my iPad - so it's pretty slick.