I presently have a mid 2010 15" MacBook Pro & in the market for a 2015 15" MacBook Pro & my question is how much storage I need? To upgrade from 256 GB to 512 GB is approx. $240.00. I presently use my MBP for emails, photos, editing & projects, iTunes & surfing the internet. On my existing 320GB SATA Disk there is 228.18 GB available of 318.84 GB. Any suggestions would be appreciated.