I also think a 17 is too big and imo, a 13 too small. I referred to the 13" specs because you were talking about the 13" MBP. The 17's also don't seem to have as many options and performance as the 15's do.
Heck, we use a 21.5" iMac to dj with. Works great and no eye-strain. And we don't look like every other dj, who uses a laptop. Not that there is anything wrong with that.