Moving speakers from downstairs to upstairs, degrading ?

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. 

I have to agree with the majority, suspended floors sound worse than concrete slabs. 

I can speak from experience. 

Bass will sound flabby compared to slabs. 

Decoupling the speakers from the floor is your best bet.