Properly paring motor and battery voltage

Friends
The original idea for the project I'm currently planning out included a Phaserunner, 3000w QS hub motor, and a beefy 72v/34Ah battery pack. The plan was to govern the output to
3000 watts max via Cycle Analyst to give myself the peace of mind that no matter how hard and long I run the bike, neither the motor nor controller would break a sweat.

However, I'm also starting to entertain the idea of swapping out the 72v battery in the above configuration for a 52v so that I could incorporate components such as Luna's Remote On/Off Solid State Switch. The added safety would also be a welcome benefit.

If I do decide to down-spec the battery, should I also down-spec the motor? The cost and weight differences between the 2kw and 3kw QS motors is quite small, so those two factors aren't significantly influencing my decision. Are there any real detriments to paring a 3kw motor with a 52v battery, or would you recommend sticking with the original 72v plan?

Voltage determines the rpm of the motor so it depends how fast you want to go. There will be a big speed difference between 52 and 72v.
I would stick to the 3kw motor as it is future proofed if you want more performance. No need to down grade, especially if they are similiar weight. There probably isnt much difference if any between the two motors.