the nickel is probably there to make for a balanced sound.
does it sound too bright, compared to the other strings?
If you plan to jam mostly unamplified, get some acousticores and you'll have the best chance of maintaining a presence w/ those bright 6 strings, banjos, and whatever.
If you want to amplify and are looking for a nice, balanced sound, you may want to consider singles:
On my fretless acoustic 5, I'm working with nylon tape B, Bronze E, A, and Nickel Flat D, G. Good thing I never replace strings...

I EQ the high end down down down and it sounds pretty close to a double bass.
Have fun!!!