We're still planning our migration from 5.0 to 6.0, so I don't have any personal experience with the process. We are planning to tackle the work ourselves, but we've done a lot of custom development, so we're pretty comfortable with the OpenERP code. If I were inheriting the system from someone else as it sounds like you are, I would be very tempted by the support contract that includes doing migrations for you.
In addition to the paid service, there also appears to be an open-source tool available for running data migrations. It is also discussed in several forum posts. (There really are a lot.)
Our tentative plans are:
- Try out the migration tool for a demo database from plain 5.0 to plain 6.1.
- Migrate the code for our custom modules to 6.1, following the Pragtech guidelines.
- Extend the migration tool's configuration to cover our custom modules and any others that weren't included with the tool.
- Run the migration on our full database into a sandbox and test the heck out of it.
- Launch and celebrate!
Update:
We've started our migration process, and we're using OpenUpgrade instead of the Domsense tool. We never really looked at the Domsense tool, so I can't say which is better. I'm very happy with OpenUpgrade so far.
In general, I've found version 6.1 much easier to customize than 5.0 was. So far, I haven't had to change any core modules. For example, most places where a core module inserts a record, it calls a helper method to prepare the data. If you add a new column that you want to be populated, you can just override that helper method. For example, we added a grouping field to several tables and then wanted to copy it from sales order line to stock move. We overrode the sale module's version of sale_order._prepare_order_line_move() with our own version.
I posted a separate question about customizing reports.
The down side is that every customized feature we try to migrate requires some change. So far there has always been a change in the core module that somehow breaks our customization. Either a field name changed, or the screen layout changed, or the whole model name changed. You can usually figure out how to fix it, but everything takes time.
