Well Yeah, You're gonna hurt them, but they are still gonna take it SO MUCH BETTER than anyone else would.
In any case, no boxer is gonna just stand there and let you hit him with your bare fist. That's like me saying 'IF RONNIE COLEMAN WASNT ON STEROIDS, MAYBE I COULD BE BIGGER THAN HIM, its your little daydream.
He'll have hit you 3 times before you even have a chance to make contact. And even if you do work your magical ground skills, you're not gonna get too much power on the ground. Plus, it's not gonna go the ground because you'll already be unconscious before it has a chance too.
Seriously, what are the chances of a pro boxer at least getting in one punch in a fight between you and them? I'd say very very high. Let's not forget that this pro boxer is gonna have bare knuckles too...
So... Pro Boxer+Bare Kuckles+at least 1 shot on you = You on the floor, battling to live.
The funnier thing is, you aren't even talking about any old pro boxer, you're talking about the best! That's really just taking the piss.
Anyway, Why don't you go and start a fight with a top boxer, take a video camera for someone to shoot it, and report back if you're still alive rather than shouting your mouth off about how you could take these 150lb boxers because they're only small.
Love internet tough guys.