I know that Im coming late to the dance here, but I mainly brew 2 or 3 gallon batches for a number of reasons. What I really like is that I get to brew more often, which means that my ADD brain forgets less between batches. It also means that I can tweek or modify a recipe while it is still fresh in my mind (or fridge), giving me a more tangible reference thank just my notes. Also, I am the one drinking most of whatever I make, so smaller batches let me have some variety.
A myth that I can dispel is that it is budget minded. I spend more per batch because even though Im only using an ounce or two of a specialty grain, or an 1/8 of an ounce of a particular hop, I still have to buy a minimum of a pound of that grain or minimum of an ounce of that hop. Even with more frequent brew sessions, I still end up throwing out a good bit of grain and hops because they go stale.
All in all, I like making smaller batches because I feel that the advantage, for me anyway, outweigh the disadvantages.