Hi DCD thanks for the comment.....just checked my manual (Newer RAT installed) On FCOM 3.02.24 pg20, the ND 1 is lost in flight when the electric network switches over to BAT at appox 100 kts.
So I guess for both the Older RAT and Newer RAT, they have the same property of shedding the ND 1 when the BAT connects to the Elec Network
As for GEAR down at 1000ft , even tho my manual is silent on this, It makes good sense to delay it as per your reasoning.
Regards