No idea, which is why we offer a free test service.
The free test is designed to discover if EcomExodus can maintain data integrity for your site.
The process is:
You can then review the results in our "View Stored Data" tab for the transfer, if the data looks correct you can write the test data to your destination
to fully test the process.
Possibly, data validation rules vary from platform to platform and ExcomExodus uses a flexible middle model to allow transferring your data to different platforms.
EcomExodus will try and fix the most obvious examples like WooCommerce allowing duplicate SKU's when no other system will allow this.
OsCommerce, while requiring an email address for a customer does not care if the email address is valid.
Shopify however does a reverse DNS lookup on the addresss so will fail "firstname.lastname@example.org".
That customer will not be able to be transferred to Shopify without fixing the source email address.