Personally I would put in jump drive decay so that it diminishes jump range. Misjumps and about 50% jump range when it's near zero.
I was thinking about that the other day: wouldn't it be cool if you could overcharge your drive and make jumps 2-3 times longer than you normally could, but you damage the drive each time and you have a nonzero (and increasing with damage) chance of winding up someplace completely different?