I had one bike + front rack combo that wasn’t nice at all.
Or rather, it did OK once at speed, but getting off to a clean start was near enough impossible. It always took a fairly bad wobble before it started to track straight.
Not a good thing for an urban/suburban commuter.
Possibly tolerable for an open-road tourer.
I’ve also tried other bikes that didn’t seem particularly troubled, at least not at moderate loads.
Exactly what it was that made the nasty combo nasty, I don’t know.
Maybe rack flex, maybe fork flex. Maybe something in the geometry.
Either way, I wouldn’t hesitate to try front rack only again.
But I’d be ready to reconsider If experience showed it to be a bad idea for that bike.