Yeah, I shot some Optima 100 in 4x5. It was a nice film but not particularly remarkable. I think I have a few sheets still frozen but no idea how well it will work now.
But Ultra 50 was unique, kind of like a negative C-41 Velvia, only even more saturated I think. Of course you can just scan now (or shoot native digital) and crank up the saturation if you want. Any damn fool can do that and too many do. But back then you were more limited in ways to get that kind of look. It wasn't for everything any more than it is now, but when it worked it really worked.