Things get more rattly on an empty bike, but even that hasn't bothered me. I'm a casual rider, so maybe that's a part of it, but I actually quite like how Bullitt handles.
I quite like how they ride as well, I just take it a bit easier than I would like down hills and on the flats if the bike is empty! It's annoying because our depot is down hill from nearly everywhere we deliver to so we're always going up hill with a full bike and down hill with an empty one
Things get more rattly on an empty bike, but even that hasn't bothered me. I'm a casual rider, so maybe that's a part of it, but I actually quite like how Bullitt handles.