Well the locomotives you mentioned were simple design and effective.......
A P-5/P-7 is highly quality full of electronic circuits and full-time power electric circuits.....
Now it is a known fact that electronic items don't have the durability of their simpler electrical predecessors!!!
Electronic circuits are vulnerable to permanent damage if taken out of their tolerance band!
That...
more... is the reason why I feel that P-5 can be suddenly overfed by the proposed, upgraded transformers! Surely that would risk component failure....
If they are upgrading the Transformers then surely they will have to redesign/replace some parts of the locomotive...