Total Posts: 653
Buenos Aires, Argentina
(Saludos en español entonces)
About that products quantity, I got a bad experience with Magento Dataflow.
I made import of 22k products, but using my own scripts, that make the inserts on all the tables. These scripts have my adaptation to use my select data source.
I understand that Magento Dataflow need more work for import too much products at once.
If you want to try, maybe I can help you or guide you with the process.