there are too many bikes out there to make a blanket statement about how each suspension works.
+1 on that.
Don't forget DW Link and Maestro.
In my short biking career I have had 2 single pivots a horst and a faux bar.
My 2 single pivots were fine bikes. They both had their pivots in a different location. They were both decent pedlar's but I think that was mainly due to the platform shocks. One of them had noticeable brake squat that was very annoying. The other was a fine bike that I would not hesitate to purchase again if I had to. Simplicity of design is the major strong point with SP. They do the job with minimal fuss and for the most part modern shock technologies have addressed their major weaknesses. Also if brake squat is a major issue you can equip most frames with a floating brake.
My horst bike suspension rode like a dream. It kept the rear wheel planted and was very smooth. I did have some problems with one of the rear pivots. It constantly loosened up and dropped the bolt. It happened to me at the squiggy race and once when I was about 25 miles from my car. I started carrying a spare bolt but that is a pain. No amount of locktite or other remedies would correct the issue. I am sure it was an isolated problem but I use it to illustrate that more pivots = more potential issues. I eventually sold the frame because of fitment issues.
My Faux bar bike also rides great. To be honest it is so similar to the horst I would have a very hard time telling them apart in a blind test. The one issue I have is that sometimes when going over an obstacle the rear pops up and hits me in the butt. I really think this is a setup issue (shock) and not something inherent to the faux bar design.
My personal opinion is that a well designed bike will ride great no matter what suspension system is used. There are so many factors that can affect ride quality that one must look at the whole bike and not just one aspect. But of course bushings and 29" wheels make everything better