Hi,
Regarding the demo.xml file, I tried the following scenarios:
- having the <data></data> empty, resulted in no import (logically :)) 
- with several records, resulted in filling the list. 
- with existing records, tried to modify a value in the first record, 
 the value was not updated - Why ?
- with existing records, tried to remove or comment a record, the record was not deleted 
- with existing records, tried to remove all records, nothing was deleted 
- tried to create a new record, the record was created 
 Can you help me out with this one, please ?
 
                        
This is my demo data: Object 0 110 0