Moving speakers from downstairs to upstairs, degrading ?

its way more than the slab vs suspended floor. Its the structure (walls, ceiling, etc.) and how live that is. You shall see. As I can since i just built anew music room on the upper floor, and empty its a freaking echo chamber. I have much treatment to do!

It will be a downgrade I guarantee! You will lose bass as other things will absorb it. Objects flooring etc. 

Almost a dumb question as youve probably found from the answers .  Try it and see . 

+1 to itsjustme. The other acoustic factors will totally overwhelm the effect of the floor and the carpet. There will likely be a large difference in sound unless the rooms are sized and furnished identically. Both flutter echo and bass nodes will be whole new problems in your upstairs room and you will need to start from scratch in controlling for them.

Carpet over concrete is much better than hardwood floors although the greatest benefit will come from acoustic treatments on the walls and ceiling.