If a player got injured in 1,6,7,9 I'd rather Hornby were there to replace them than Gidley. It would be a more seamless transition with him there because he's very adaptable, doesn't overplay his hand and will always do what is best for the team. The team dynamic would change with Gidley there...and that's not what you want from a fill in. He is more likely to get in everyone's way, run the ball himself and try to do something on his own instead of working to whatever the original plan was.
In saying all that I wouldn't have either playing Origin
In saying all that I wouldn't have either playing Origin