Thanks, I've read a lot of similar product reviews and opinions from those who, like me, have used dirt and wood and even rubber mats.
Each of them have their benefits, I find that rubber mats are often given a positive review when in fact, as was documented in one of the forum posts, they can be extremely dangerous as a mat over concrete, I've seen a similar situation to the one referred to in that post.
From my experience dirt is the best for footing but most difficult to clean. Concrete is the easiest to clean but is hard on the horses legs and can be dangerous when wet, even more so during winter months. Rubber mats are better to clean, easy on the horses legs but can be as dangerous as concrete when wet. It should be noted there are different types of mat floors, some are constructed of much softer rubber and provide much safer footing than the harder rubber mats.
I had written in another post here some time ago how happy I was after replacing our run-in floors with poplar. Used in the flat-beds of trucks it is rot resistant and takes the wear of horses hooves over time. It was three years ago now I believe, 12' 2.5" X 8" boards supported every 6' by a PT 4X4 and after we sweep the sand and crud off them we are amazed how well they have stood up. If we choose to go with wood it will be a poplar floor again. Thankfully there is lots of it on the property and it is a rapid growing weed tree.
The more I write about it the more I'm convincing myself wood may be the way to go.