May be, may be...
But some open sourses that I've seen says that 53T6 and PRS-1 is the same missile.
And that could be the problem. Actually, C-225 wasn't intended to defend cities. It was intended to defend fortificated military objects wich could withstand atmosferic termonuclear blast at a range of 10-30 km without any damage. But Moscow is not a military object (mostly ).
So I hope, Mr. Podvig is right. And 53T6 is a really different, upgraded missile with conventional, fragmentation warhead. Because otherwise Gazelles also stays on duty with those "concrete" electromechanicall warhead eqivalents. And thus they are useless...