Mavericks runs fine on my unibody late-2009 white. However, I upgraded to 8GB ram and a SSD when still in Snow Leopard (both aren't really necessary). Comparing to Snow Leopard, Mavericks provides better battery life. If you're a developer or have a Crossover license, check if you have licenses that support 10.9. For example, nVidia CUDA drivers doesn't work with 9400m + Mavericks.