EDIT: What are the stall speeds on Earth for the XRs?
The XRs are delta wing planes, they don't have a stall speed as such. You just loose lift until you drop like a stone.
Also, stall speed is the wrong number to look for during landing. You don't want to stall, you want to fly on the runway with enough control over it.
From the basic flight school of Urwumpe, for getting used with any winged vessel:
Landing starts with the approach. As we do spaceplanes, approach means energy management and alignment. We want to reduce the speed so we are not too fast, and align with the runway at the right distance. The best way to do so is the HAC approach.
This requires some training to get the targeting right, but is generally more successful as copying jetliner landing strategies. Usually, you will do a overhead approach: You pass over one end of the runway in 11000m altitude, and count to 10 (roughly). Then you do a steep turn towards the runway, loosing altitude quickly. While you gain maybe a bit of speed that way, you will loose most energy to drag. At the end of the turn, you should be roughly aligned with the runway.
If you are too far away from alignment, change the time from passing over the runway to initiation of the HAC turn. My experience is, that you can eyeball it pretty easy, and also can integrate nav beacons into it.
Practise to end the HAC in about 2500 m altitude and about 6000m distance to the runway (25° glideslope). This is the most critical part, but can be learned easily.Using the HSI and ILS is recommended, as both help you to manage the turn and get out of it right on the glidepath to the runway (the vertical plane passing through the runway).
Drop towards the beginning of the runway lights. In 500m altitude, start to pull slowly up (preflare) and point the velocity vector indicator at the point where you want to land. You should now also intercept the 3° ILS glide slope. You will loose speed quickly now, so be prepared to pull gently up over time to stay on the 3° glide slope.
In 150m altitude, lower gear, if you didn't do so. You will now loose much more speed. Pass over the runway threshold and pull up (flare). you will now quickly loose vertical velocity and even more quickly loose speed to the increased drag. If you do the flare at too high altitude, you will drop hard on the runway.
In this appraoch, speed is everything. Too slow and you will drop before reaching the runway, too fast and you will have problems getting on the runway with main gear first. My personal rule: You are too fast, if you can fly on the 3° glideslope without having the nose above the horizon.
The real numbers depend on the plane you fly. Instead of learning to fly by the numbers, learn to trust your eyes and feeling and use known numbers only as rough guide to the runway.
Any landing is successful, as long as you get down in one piece and did not overshoot the runway.