1 - 2 horas
I replaced a bad hard drive with a solid-state drive. I wanted more storage capacity, so I replaced the rarely used optical drive with a second hard drive.
Very smoothly with the guide. It took about 30 minutes total.
Big impact on battery life. Maybe 3 hours if I'm careful. I used the "ditto" command in terminal to replicate my home folder from the SSD to the new drive. Then changed my home folder location in the Advanced Settings under my Account in the System Preferences. I left the original Home folder on the SSD. Cloned the SSB drive as a backup for easy restoration. The SSD is only to be used for OS and applications.
MacBook boots in 15 seconds.