Would the show had been any diff'rent if Judy stayed on the show for all 9 seasons on FM ?

Well if she were, the show would have avoided making one of the biggest inconsistencies in TV history. The Winslow's would also have a younger child, so while Eddie and Laura were in college, Judy would have been in high school.

She was not that bad of a character her only problem was she was not as outspoken like her sister laura she was kinda the shy girl who runs to her room when she is afraid,the producers could have gave her more speaking lines between her family and mr steve urkle at times it seems like the girl was just a black sheep of the family lol

She wasn't really shy, the writers just never gave her many lines. She's made sassy comments to Richie, Laura and Eddie.

Yeah all the lines were for carl,laura,eddie and mostly steve since they were much more popular characters then her