On some cameras superfine is TIFF. I find TIFF a little impractical for digital cameras. If a camera has raw I use it almost exclusively. But a 5Mp camera takes a 14.4 Mb TIFF. That fills your card, but worse overwhelms most buffers and you are often waiting for writes.
If superfine is a JPG mode it is a good deal. Only better cameras have that and a 5Mp superfine image is only around 3.5Mb. Most buffers handle that and it is worth it to get a card large enough to use it almost exclusively.