I'm torn between getting a maxed out 13" MBA or upgrading my war torn late 2008 15" MBP with an SSD and new battery. 12 hour battery life and portability is tough to beat and speed sounds like it would be an upgrade minus the dedicated GPU but I have an iMac to take care of the heavy lifting...Anyone in a similar position have thoughts?
If you had told me you had an early 2011 MBP, I'd say stick with it and put an SSD in. But 2008, you've got a number of performance and accessibility improvements that make the new MBA a better choice for the long haul. You get thunderbolt, USB3, AirPlay mirroring in the OS, Recovery Partition, the old MBP will be EOLed on OS X support any version now while the new MBA will be good to go for years yet, etc. You've given it five years. Go ahead and make the jump; it's time.
/jumped from 2009 MBP to 2012 MBP and it was worth it