Thanks very much, exactly what i was looking for. Really helpful. Think I might just wait till the new machine has decent discount and then reconsider.It'll probably last 10 years like the current one.
10 hours more battery life. (on Paper).
CPU IS at least twice as fast.
SSD is 2x to 3x as fast (depending on configuration).
Better screen (brighter & better contrast ratio).
1/4lb lighter.
Much Better Webcam.
Silent
Will support more up-to-date OS features.
Most of all it won't cook your Gonads if you are watching youtube videos.
But specs aren't everything. If you are happy with the current machine, and it's fast enough for your daily needs then there's no real reason to ditch the ol' girl yet except to treat yourself. Personally I prefer the keyboards on the older Macbooks.
Last thing to bear in mind, is that your current Macbook might be worth $300-400 depending on it's condition.
Thanks again