I prefer to listen to my music on my laptop in Apple Lossless at home. On the go however AAC is fine, and a must, as I don't have enough space on my SSD.
Itunes has the feature to automatically convert AL to ACC when syncing with an ipod. Could this be replicated to work with another mac too? I would then have my master library (with AL) aliased to an external drive I hook up when at home, but when on the go it would fall back to my slave library (AAC) on my local SSD.