On 2nd thought if you use a chair with casters ,hard rubber sheets would be better. Like the type for horse stalls.
Even so, I've lost a razor to the concrete floor. Unless the foam is wall to wall, razors have an internal targeting device for concrete.
You can't roll casters on these, but they provide plenty of cushion! Definitely add some style to any man cave.
And I guess the more hollow the grind, the more likely it is that it will fall between the cracks and hit the hard floor edge first!