I have a 13 inch MBP early 2011 and i had upgraded the memory from 4gb to 8gb and hdd from 320gb to 1tb last year and I'm thinking of getting an SSD and I'm not sure what to get i was looking at: OWC DIY Kit: Data Doubler + 120GB OWC Mercury Electra 6G SSD Drive Bundle + 5 Piece Toolkit. $139.40 which is on sale now $119.99 or OWC DIY Kit: Data Doubler + 120GB OWC Mercury EXTREME Pro 6G SSD Drive Bundle + 5 Piece Toolkit. $179.49 also on sale $159.00 and thinking of using the data doubler to use normal hdd instead of optical drive and have the SSD as the main drive would it make any noticeable difference if i go for mercury extreme over mercury electra and should i use the one TB HDD that i bought last year or 320gb HDD that came with my mac in place of the optical drive. i currently have my 1 tb hdd partitioned in half and I've used about 250gb out of 500 in my main partition and my second one is empty since the 1 tb hdd is bit more noisy should i use the 320gb in the data doubler and have the 1tb hdd in external enclosure. so what 2 drives combination is good for me. I'm planing on keeping my mac for another 2 to 3 years and will this affect battery usage and does ejecting the 2nd hdd when not in use help improve performance, heat and battery.