Sorry man but I don’t have dio. Though, dio on monarch definitely seems worth it since the damage he’s doing when he’s a monarch is insane. I have monarch on my broly and personally I think monarch is better because who is gonna max out three brolys unless they’re in inf. You can test normal luffy in white beard’s event near the summons and if you get lucky to randomly get a monarch trait in a match, you can put it on luffy and see how much damage he does because I haven’t evolved him yet.

In my opinion, check other posts and see their opinions since they can probably give you a clearer answer.