Yes it is substantially better because it grows in sea water. Which is to say that it is self healing with respect to erosion. They give examples of roman marit

Yes it is substantially better because it grows in sea water. Which is to say that it is self healing with respect to erosion. They give examples of roman maritime concrete that is over 2000 years old and still functional. No existing concrete does this (hence the DARPA call for research topics). It is also why a concrete hulled boat using this stuff would not suffer hull erosion like the existing cement fleet did during world war II and afterwards. It isn't clear to me (but I've not found a good paper on Roman "maritime" concrete either :-)) how it interacts with barnacles and other marine life.