There's not going to be any more drop in performance than there would be with a poor quality cable. All there is is a power IC on the adapter board and that's most likely there to cope with SATA power connectors that don't supply 3.3v.

Nice to see these being reviewed. Some Shuttle XPCs have an mSATA connector on board, potentially very useful for such a small system.

I believe that the Intel NUCs also use an mSATA drive. And Shuttle PCs are large compared to NUCs.