Yea, we now have the unfortunate situation of recording with everyone scattered across the US. So we send parts back and forth, adding and replacing parts.
We've found that it's a lot better if things are aligned to the grid. When we do get together once in a while and lay down tracks, we too like to have a little human sloppiness, but we can be "sloppy together" if there is interaction between the players. That doesn't work so well when you're just playing with the other parts.
As a side note, I find it very interesting how the brain works with that stuff. We have songs from years past that were recorded without metronomes or grids. There is a lot of sloppiness in many of them but it doesn't really bother anyone, sans maybe some really good musicians who might pick up on it. Same goes when we get together now, we can record things where we're all together but it slips or gains a bit here and there with no problem.
But if I take one of those tracks and align any piece of it to a grid, it gets all out of sorts. Basically, at least for us, you have to either leave it alone or align it all to the grid. Anything in between just plain doesn't work.
gabo