In open water warfare the T42 definately has the edge over a T23. 180nm+ radar range with a quoted 35nm range weapon in Sea Dart. Woodward says in his book that (when its working) it can take down a four ship formation at 15 miles. The new versions (which may or may not have autopilots) are much more lethal than the Block 1 types used in the Falklands. But... the 909s still can't track targets flying low over land, so iI guess it is of less value than a T23 close in.