I worked for apple back in the days of a real job. That is a great Mac. 2.7 (I am guessing dual core i5) is a good processor speed. 16 gigs of ram is more than enough. Other thing to consider is hard drive speed. 5400 rpm is not that good. 7200 rpm is good. And of course SSD or a "hybrid" drive would be excellent. And yes, new macs come with 10.9
But that is a new OS and if the one you have comes wiht 10.8 you would be better off. Also if you do decide to upgrade to 10.9, it is free!
Last but not least, make sure to get an external hard drive. You never want to record onto the same drive as your system drive. It can run into problems and even cause sessions not to record properly. Any questions feel free to DM me.
Bassist of Sakara, rock band signed to Pavement Entertainment. Debut album being produced by Johnny April (bassist of Staind). www.facebook.com/sakaramusic
Jazz Bass Club #1216