I think the commonality of their opponent doesn't have much relevance, Rashad has improved 10 fold since that fight, if he faced Ortiz today he would most likely TKO him, back then he was a very, very green striker and was almost all wrestling, hell people thought he was boring blanket back then. Now he's knocking out people left and right.
I think if Rashad comes in with a good game plan and mixes it up and is able to be the stronger more physical person in this fight, he has a good chance, if he turn it into a striking match it will be rough, he needs to clinch, dirty box and take him down and grind him out.
It will definitely be interesting, Machida hasn't been tested and who knows if Rashad will be able to test him, if he is able to then it should be and interesting fight. I think this will be Machida's coming out party, it will show how good he really is or how over hyped he is, no one knows which one it will be until the fight goes down.