Sometimes, the leader has to make a tough decision that won't please some people. Not every song is gonna be comfortable for everybody, even if u change the key, so just try to accomodate as much as possible. If no agreement can be made, I say scrap da song until your singers can pull it off.
I think that Eb is a middle key, well anywhere between D & G. Sometimes, u can sing lower inversions or like sjon said switch parts for certain portions of the song.