I would stay around until better project came up. Then correctly explain the situation and say good buy. I would not call it a "let down" from Your side. Just...time goes on and things changes.
Unlined or lined - Your own choice, but i guess it does not attend to sound. As to strings, for 15 years i preffer on my 5 string lined fretless - d'addario roundwounds, nickels, 45-135.