Nothing is going to keep the NSA away
They either pressure the Dutch or UK govt to give them access or just run a fibre tap into Germany's major exchange
The advantage of keeping the data in the Eu is that if all your medical records suddenly show up on a US life insurance company's marketing database you have somebody to sue, and they can't get their brother-in-law the judge in East Texas to rubber stamp it.
Also your cloud data can't be subpoenaed by a US competitor, again with close family ties to E. Texas courthouse, quite as easily.