I work on a 2008 iMac, running 10.6.8. When traveling, I clone it onto an external SSD (using SuperDuper), which I boot up on my 2010 MacBook Pro. When I return, I clone the SSD back onto the iMac. This works great for me. But I would love to get an 11" MBA to use during my trips because of its size. I assume that one cannot clone an Air to an iMac and visa versa. Is that so? If not, great. If so, is there a strategy I could use to accomplish the same ends, short of laboriously and inefficiently copying new and modified files back and forth?