Love talking this stuff. I've played upright bass off and on since the '70's, but I've only been in one organized four piece group. We were all decent players, but our singing far exceeded our playing in terms of quality. All four of us could sing 3 parts without any prompting, and we were quick to correct one another when a stray note or two showed up. An no one got out of shape about it. It was always for the better. Best song we ever did, from my standpoint, was the Eagles' "Seven Bridges Road". I love singing that song..a true test of harmony and timiing. Also did the Gatlin Bros. "Just Wish You Were Someone I Loved". They get into the harmony on this piece by piece, and they kill it. Straying off, gotta stop.
Oh wow, I just heard that Gatlin song the other day for the first time in years. They had awesome harmonies.
Yes Seven Bridges is a great piece to do. We did it in my previous band only as 4 piece, minus Don Felder's part. Would've been great as 5 but we did ok.
Yes I've known bands who's playing ability was good, but their tight vocals were what set them far and above; they could carry a show without any music.
My wife's cousin's band was such; 4 guys, each one individually had a voice as beautiful as anything you'd ever hear, then put together as something that sounded like magic.
I love to hear groups like that. It's inspiring to hear what the human voice is capable of.