We're in the middle of the exact same transition. If you have direct access to your SugarCRM database, this is much easier. Export the data from SugarCRM to a CSV, either through the SugarCRM interface or by directly querying the database in a script and writing the output to a CSV. Then either reformat the data in a manner that can be understood by the OpenERP import function, or write another script that writes the data directly into the postgres database using the python psycopg2 library. We're using the latter, and it works very well. The import_sugarcrm module was decent in 6.1 but this gives you far more control, and any customization in SugarCRM won't be carried over.

In short, there's no simple way to do it, any data migration will need a few steps and some effort setting up the import script. Sorry if that's not very helpful, let me know if there's anything specific you need clarification on.

Has anyone tried https://www.openerp.com/apps/7.0/import_sugarcrm/ ?

I'd like to know which versions of Sugar support the website this module uses and how effectively the module works (It was co-written by OpenERP so I am very hopeful.)