Solution : https://service.sap.com/sap/support/notes/428989 (SAP Service marketplace login required)
Key words : 
transfer customer-specific material master fields, transfer material master standard fields, customer-specific enhancements, product master data, additional filter conditions, customer_extension_product solution read, crm/ebp system, product master, /3-oltp system, transferred data
Related Notes : 
       
| 1122266 | Mapping of MARA deletion flag in material download | 
| 872533 | FAQ: Middleware | 
| 623026 | Download R/3 status MARA-MSTAV on CRM distrib. | 
| 583933 | Reducing data exchange at sales organization level | 
| 546868 | Inclusion of customer-specific set types in product BDoc | 
| 497101 | Mapping of MARA deletion flag in material download | 
| 495764 | Description of the status in the CRM product master | 
| 451066 | Delta download for material which differs from filter first | 
| 446659 | Upload: GTINs are not transferred to OLTP as EAN | 
| 441824 | Data upload from customer-specific set types into R/3 Backen | 
| 396351 | Reduction of the delta downloads | 
| 392779 | Incomplete materials after delta download |