I think CGN at 1x daily was flawed though, I'd have said that MST was a better choice and I'm really surprised it failed so miserably.
Of the routes mentioned, Paderborn would be a good choice now it has lost it's London links which have I believe operated for many years. However, with FR eyeing massive German expansion it is a risk.
Also in Germany, Saarbrucken has some previous form from SEN and I believe didn't do too badly.
I wouldn't be surprised to see them do SEN-NQY, and maybe have another crack at Waterford