RSDDSTATAGGRDEF for aggregates statistics are completly obselete in BW on HANA.
So your idea of not retaining the entries would be ideal.
This would be useful when you do the sizing with ABAP report /SDF/HANA_BW_SIZING aswell.
(1637145 - SAP BW on HANA:Sizing In memory data base)
BR
Prabhith