I have the nlr motion plus x2 (front & back), had them for about 12 months. I know that’s not what you asked above although you did mention the motion plus. In that time I’ve had one fail (replaced under warranty but a pain and expensive to ship!). It’s good & less good for me and these are my opinions, not objective truths and I don’t have any experience with other motion platforms. A touch of buyers remorse for sure, but not too much 
On the plus side for the nlr:
- They are compact and slot in nicely to an existing nlr rig, mine are on a GT Track.
- The software is really nice and makes adjustments easy. It has most of the games you would likely need.
- The detail of motion is very good, ie in msfs you can really feel all those bumps when there’s turbulence, the bump of touching down etc. Roll & pitch are there but the effect is more subtle due to the limited movement range. Simulating g-force is not their strength so that means acceleration effects won’t be strong.
- If you’re into driving sims then again it’s the detail in the road surface that’s mainly what comes through. The bumps on kerbs, pitching down when braking hard into a corner and wheel slip are all great to have. Without the units on then no question, everything feels very dull.
- They are relatively light on power use compared to others I believe.
- Simple to setup and ‘build’. As they’re pretty much self contained there’s not much messing around.
On the less than positive side:
- They are very expensive for what they are, of course I knew that when purchased. An expensive toy but if you can afford it and are limited in what footprint your motion can have they make a viable option.
- They are quite noisy when moving, I always have noise cancelling phones on but be aware of that as it may annoy others.
- Once you’ve experienced motion and particularly when coupled with VR it makes flying without it a total snooze fest, that might not be good for your bank balance.
- If you’re after a roller-coaster effect then as said above, these units won’t do that. But, my opinion, too much rolling around gets old pretty fast. Others maybe will love that.
Overall they’re decent but there are better options if you’re looking at value for money, in my opinion. I don’t think the DOF looks that tricky to build and it does look decent but I’ve never used one. Looking back and if I knew then what I know now I may have gone another direction but that would have also meant a new rig etc. It had to stop somewhere!
When I had the unit fail then going back to one unit installed did make a noticeable difference, mainly in the driving sims, but I always had that experience of two units in mind.