You'd have to be out of your mind if you think 154 is even money. Floyd is an obvious favorite at that weight.
Davey Moore (RIP) might disagree. And Duran fought (and beat) Barkley at 160, a weight Floyd has avoided so far. There isn't any weight where Floyd would be the favourite.
He also fought a prime Hagler to a near standstill that few even thought he won. Marvin would no doubt be favored to kill Floyd.
That argument works both ways. One thing for sure, Floyd is getting hit and he's getting hit a lot. Now his defense might be able to deflect a lot of what comes his way, but then again when Duran was a lightweight he sparred with a middleweight who said that Duran hit him so hard he couldn't use his left arm for a week.
I'd pick the Duran who beat Moore over any version of Floyd at 154, so you're right, it's not even money.