I use a 15" MacBook Pro purchased in 2011
-Intel 2.66 ghz i7 processor
-6g RAM
-256gb SSD (installed last year)
-Lacie external drive for Time Machine back up

I have not noticed processing to be much faster or battery life to be longer with the SSD but boot up time from a cold start is amazing. I put in the SSD because the computer was dropped onto a hard surface and the original hard drive was damaged.