As a workaround, you can consider backing up the XSL file before running the import, then comparing the two and restoring the backup.
 I am losing the conditional formatting of the combo boxes after importing an updated schema to the InfoPath form.

 

 To reproduce:

 

 Create an InfoPath form, VS.NET 2003 + IPSP1.

 Create an XSD schema externally (VS.NET).

 Import the schema.

 Add a combo box linked to the schema.

 Add conditional formatting to the combo box, to become read only when another field is changed.

 Add more fields to the schema from outside InfoPath.

 Import the schema again.

 

 Results: the conditional formatting is lost on the combo box, but it will not be lost in the text box (if you decide to repeat the test case with a text box)

 

 I had this problem in the preview release of IP and I though Microsoft knows about it :-) , now I should be redoing the conditional formatting every time when I import a new schema :-( "and I have about 500+ controls on this form, in 40 sections by now and still growing"