In When LTE is faster than 5G, respected journalist Achim Sawall points out that DT's 5G DSS loses 15% of capacity to additional signaling bandwidth. The result, in theory, will be less capacity in the same spectrum than if used purely for LTE. He quotes a DT engineer
"A problem with dynamic frequency release is the waste of resources, because in addition to the 4G signaling channels, 5G signaling channels must also be sent. The signaling effort in a 10 MHz channel is currently around 15 percent, leaving 85 percent of the channel for the transmission of user data. 5G has approximately the same overhead, reducing the available bandwidth for user data to about 70 percent of the channel. "
Max Planken adds
"5G currently has virtually no advantages over DSS. It is all just marketing. If the network operators used pure LTE instead of DSS with LTE / 5G, the maximum achievable speed would be even higher."
Pia Habel of DT contends
"It is a fallacy to conclude that this is 'only marketing'. 5G is the target standard in the long term."
But she does not dispute that the 5G using DSS is slower than 4G LTE would be in the same spectrum. Nor does she suggest that the 5G has a significantly lower latency.
5G in bands of 2100 MHz and below may ultimately be slightly faster than 4G, perhaps 20%. My source for that figure is Neville Ray, CTO of T-Mobile USA.
Today, 4G is likely to be faster. Half a dozen technical features, especially LAA, are not yet available in 5G. LTE can comfortably aggregate 4 carrier bands, which is not yet possible in 5G.