Binding Energy and Enzyme Rate
Your intuition that the enzyme binding more strongly to substrate will be slower is correct, this is called ground-state stabilization.  I think where you might be making an error is how you handle the factor of 25.  The factor of 25 probably refers to the ratio of equilibrium constants between E and ES for the two enzymes, not the ratio of binding energies.  So you need to start with delta G = - RT ln Keq, and compare for 2 different Keq's.  Then use your equation to estimate the difference in rate constants.