The train is amazingly fast - and efficient - and comfortable. Wouldn't have missed taking it for the world (we did 2 legs - Tokyo to Shin-Osaka - and Kyoto back to Tokyo). Only problem is heaping a bunch of travel on a jet-lagged person. The OP will have to decide for herself what her tolerance is.

Actually - I thought of my perfect solution to this trip. Arrive in Narita - get meet and greet service from Tokyo Four Seasons (2 blocks from Tokyo station) - go on limo bus to Four Seasons - rejuvenate at Four Seasons that afternoon/evening - and leave for Kyoto the following morning. If money is no object . Robyn