The higher redline lets you hold each gear longer, wasting less time shifting and spending more time in the lower gears where you put more torque to the wheels. Other than that, it's just plain cool.
Imagine a turbo setup with that as opposed to a 2.5. You could use a bigger compressor since you;ve got another 1000 rpm to spool, plus you would have it spooled for that much longer before shifting.
Honestly I'd keep my 2.5 though