How to upgrade from v1 to v2

Here's the method I've used to update from version 1 to version 2 of Commerce Stock. Please test this in a development environment!

1) Do a full DB backup
drush sql-dump > ~/db_snapshots/mysite-20121001233057.sql

2) Backup the two stock fields (populated with stock data that we'll lose after the upgrade)
drush sql-dump --tables-list=field_data_commerce_stock,field_revision_commerce_stock > before-stock-update.sql

3) Disable stock management
admin/commerce/config/stock

4) Disable any modules that depend on commerce_stock

5) Disable commerce_stock (and uninstall --- may not be necessary?)
drush dis commerce_stock
drush pm-uninstall commerce_stock

6) Remove the v1 version of commerce_stock
rm -rf sites/all/modules/contrib/commerce_stock/

7) Download the new version and enable it
drush dl commerce_stock-7.x-2.x-dev
drush en commerce_ssr, commerce_ss, commerce_stock
drush cc all

8) Re-enable stock management on the product types
admin/commerce/config/stock/ss

9) Now that we have a new commerce_stock field, we'll get its field definition and then use it to alter the data from before-stock-update.sql
drush sql-dump --tables-list=field_data_commerce_stock,field_revision_commerce_stock > after-stock-update.sql

10) Now, move over the table definitions from after-stock-update.sql to before-stock-update.sql so that before-stock-update.sql has the original data with the new table definitions. Don't touch the data WITHIN the tables, just change the table structure definitions. There should be only TWO lines that change for each of the two tables (the actual field moves from int to decimal, and the final COMMENT of the tables). I like to use Vim to make the changes:
vim -o before-stock-update.sql after-stock-update.sql

11) Do another full backup, justtttt in case ;)
drush sql-dump > ~/db_snapshots/mysite-20121001233627.sql

12) Import the before-stock-update.sql dump with:
drush sql-cli < before-stock-update.sql

13) Re-enable any modules you disabled in order to uninstall commerce_stock v1

14) TEST! Make sure the stock values are what you expected. Remember, you have at least 2 full backup points you could go back to… so quickly restore one of those if anything is suspicious.