'Deserves' is the term which we railfans use as we love trains pulled by three phasers. Shri Shakti Express with a LHB rake ,which is lighter in weight would require less effort to pull it even in gradient (WDP4D with less HP rating has done it). So WAP5 as well as WAP7 are not needed for Shri Shakti. GZB WAP4 will play their role.
JAT Mail ke liye WAP5 is accepted but WAP4 bhi apna kaam aram se kar raha hai ! :-)