If it's possible to give the impression that obi was was scouring around and found only the saber, I say go for it. and having Obi wan yell out as Ani goes over the fall could be quite good if it works. That way it all still kinda works in context with a new hope. Obviously Obi Wan had to think Vader was dead or dying when he fled Mustafar. To have that NOT by by Obi Wans hand is a better way to go in my opinion.
If it's possible to give the impression that obi was was scouring around and found only the saber, I say go for it. and having Obi wan yell out as Ani goes over the fall could be quite good if it works. That way it all still kinda works in context with a new hope. Obviously Obi Wan had to think Vader was dead or dying when he fled Mustafar. To have that NOT by by Obi Wans hand is a better way to go in my opinion.