i do love batiks--I only prewash if they fail the "white paper" test--but for me that's true of most fabric. On the LA, i do loosen the frame tightness a bit for batiks as they are a tighter weave and deflect the needle more, so more possibility of a crud stitch.
i think the thing I like most about them is all the colors--a shelve of batiks is like a treasure chest full of gems!