From city center to city center by train vs airplane
Rough estimate for a flight:
- 36 min train from Gare de l’Est to Paris Charles de Gaulle Airport
- 90 min arrival before your flight (security, check-in, gate closes before flight leaves, ..)
- 100 min flight time
- 20 min getting out of the airport
- 30 min taxi to Berlin Hbf (assuming no traffic)
I think if you have large bags you can add an extra hour (max) even as check-in will take longer, and you'll have to wait for your bag.
Which makes it 8,5 hours vs 4.6 hours, or 5.6 hours with bags. (I added 30 minutes to the train as you probably need to be there a little early.)
Having done this a couple of times (Amsterdam to Berlin, which is about the same) with both modes of transport. I have to say I prefer the train if I have the time. Much more relaxed way of transportation. You can work the whole way there, and there are ok lunch options on the train.