Before we get lost in generalities, it makes sense to state the goal of the radar.

If it's deep penetration, magnetic dust limits the depth.
If you just wan't to remove surficial dust layers, it wouldn't make that much of a difference.

I doubt given the size and complexity of a high resolution SAR mission (like the space shuttle missions), that we'll see one in the near future.

Besides, would it really be that much higher resolution than the final MOLA dataset? With high resolution radar or lidar, the capability of returning large quantities of data needs to be in place. MOLA accomplished the mapping slowly over several years.