Is it Possible to 'Downgrade' Sat Nav?

Forgive me if this has been asked before, but has anyone tried to downgrade the Sat Nav software to something like the older RRS version that I understand is much better than the version on the RRE?

My MY2010 RRS had what would appear to be the same Sat Nav hard drive-based system as on the Evoque, and from what I remember to update the software you just inserted the DVD into it and it would update from that. I just wondered if anyone had tried feeding a DVD containing a better/older version of the LR Sat Nav software into their Evoque? Chances are it wouldn't work but it might be worth a shot!