On the one hand, I hear well respected martial artists end conversations with comments like "Well a good boxer would..." as if we who "play" in the gym could never measure up. To some extent, there is truth in that. It's one things to shatter air molecules with emotional content. It's a second thing to actually hit something or someone. And it's something altogether different to attempt to do that while your opponent is trying to take your head off. I don't care what kind of techniques you think you will use on the street, do you actually practice them full force on an uncooperative opponent while (s)he is attempting to do the same to you? That's very, very different.
I've personally seen Muhammed Ali more than a few times back when he lived in Rockfish Gap south of Charlottesville. With all the protection of those gloves, it's clear that the man still suffered in the ring. He is now permanently and seriously disabled. How many of us can claim to have taken that kind of abuse?
On the other hand... That's professional boxing, and a handful of fighters in the upper echelon. The best of any martial art are to be feared. I wouldn't want to meet either Iron Mike or Royce Gracie in a dark alley - whether you want to call it sport or MA. But...the vast majority of boxers wear Fruit 'o the Looms just like the rest of us mortal MA practitioners.
When I began to train with the Charlottesville Boxing Club (a Parks and Recreation activity in the Charlottesville "inner city"), I had...oh...maybe 4 years of karate and some weight training under my belt (I was not yet a black belt). Back in the mid seventies, a "karate man" seems to have had some currency on the fear front - deserved or not. Well after the coach taught me a right cross and left hook, he brought me over to the bag. Cooool!! I may not have been particularly graceful, but I could put a hurt on the heavy bag. In any case, the boxers all stopped when they saw the "karate guy" hit the heavy bag. It was...different from what they were used to seeing. I buried my punches in that bag.
Mind you, a handful of those dudes would have been more than I could handle. However...nobody would spar me. They were...scared! Of me, the geek. Imagine that!

The unknown always does generate quite a bit of fear. That's why I love to jump into those arenas - so I can bottle that fear.
Call it what you want, but those boxers respected me, and I them.
- Bill