Questions about MBA performance

[mgpg89]

I'm a musician using Ableton Live with some USB-connected hardware for live performances.
The machine I'm currently using is a 5-year-old 15" MBP 2008 (unibody) with 2.8GHz Intel Core 2 Duo and 8GB RAM (1067MHz DDR3). I also replaced my CD/DVD-drive with an additional hard disk, so now I have a 128GB SSD (for apps & OS X) + 1TB HDD (for music, movies, etc).

I'm currently looking to replace this machine with a 13" MBA with the following specs:
- 1.7GHz dual core Intel Core i7
- 8GB 1600MHz LPDDR3
- 512GB SSD

Now my question is simple: which one is the superior machine?

(My current laptop is still running fine, but I'd like the portability and battery life of a MacBook Air)

 

[whtrbt7]

Newer MBA is better in speed as well as battery. Only issue will be storage but you can always carry an extra HDD with you for that. You can also use the built-in SSD if that is enough storage.