It takes about six & half hours on the train - that´s city centre to city centre. Fly boys need to factor in an hour to the airport, 2-3 hours check in, an hour back from the airport & the flight time. So there´s Little in it - except confort verses non-stop hassle, panic & being treated like a piece of cargo.
Bit disappointed with the initial views from the train as central France seems like a gigantic farm, but that´s because the new high-speed route avoids towns & cities. Half way though the journey we get mountains, them coast & finally the magnificernt mountains bordering Spain.