Have taken this in Europe, was really nice, and I consider this quite competitive with inter-European airlines: It saves a lot of time, because you can use cen

Have taken this in Europe, was really nice, and I consider this quite competitive with inter-European airlines: It saves a lot of time, because you can use central train stations instead of transfering to/from the airport, and you depart late in the evening (get full use out of the departure day) and arrive somewhat early in the morning (don't lose much of that day, either). So it does not have to be cheaper than an inland flight, it just has to be competitive with flight + 2x transfer + hotel, and while it might be slightly less comfortabel than a hotel room, you avoid airport transfer and -security, which is nice.