Hei
I did som testing and found that Road&Recreation only use half the amount of memory, compared to MG.
When I selected 9 tiles in Chicago area with MG US 5.0 I got 15MB
I do not have RR US, so I did a test with MG 5.0 and RR 4.0 of the exact same size area in Paris.
MG 5.0 used 4.53MB
and
RR 4.0 used 2.07MB
So to get more maps in Legend, use Road&Recreation.