Can i use dataflow import to update products

Here's the steps I follow when running updates through Dataflow:

• Export all products via 'Export All Products' Dataflow profile. System -> Import/Export -> Dataflow - Profiles -> 'Export All Products' -> Run Profile -> Run Profile in Popup
• Edit the exported file, updating the information you require (The exported file location by default is 'var/export/' from your magento installation directory) and save.
• Locate the 'Import All Products' data profile (same location as Export all products).
• View the 'Upload file' tab, upload your new CSV containing updated information and hit 'Save and continue edit'.
• Then Select file from 'Run profile Tab' and Run profile in Popup.
• Enjoy the incredibly slow import!

These are the steps i have followed many times so i'm confident they will work for you.

Let me know if you would like me to make the steps above more in-depth.