I don't need to replay mp3 or other audio files, I only replay midi files. The 3k does a perfectly good job of playing midi files and displaying embedded lyrics, and can easily set up the "next" song whilst you are playing the current one. Not as good as a full playlist but then my partner and I change our minds about the best "next" number about three time in each song anuway so this is not really a big issue!

With 128 meg on the smartcard (so thats conservatively about 1000 songs) and anything you like externally (shall we say a 1 gig thumbdrive, or over 8,000 songs) I would personally just use the 3k on-stage and forget the laptop, as this would be one more thing to go wrong.

I agree the laptop has other uses, but I don't think they alone justify the extra complication or expense.