There's already been a thread for this somewhere i recall. Basically, no. It arguably has a very slight reach advantage but it's really not by much and is otherwise identical. Also, it always makes noise, so you can't sneak effectively.
I'm always paranoid about that fact, and constantly amazed at how seldom people actually hear the choppa before I strike. Maybe it's my crazy trans-pacific ping buying me a quarter-second delay before people hear me closing in. Maybe it's people being unable to hear anything over the sound of HOW AWESOME THEIR GUNS ARE. (Queue the scene immediately following cannon training drills from Master and Commander.) Fortunately, it rarely seems to come into play for me. (Low ping mileage may vary.)
I suspect people don't listen for it. I tend to, for the most part. It may be some of the Alienware Audio software i have but i can hear footfalls and chainswords rather well, so i for the most part know when someones about but can't see them. Doesn't happen with Scorpion Chainswords, though. I don't hear those at all unless their attacking.
Ta put it shorrt, u dun wont eitha of them. Wot u wont, WOT U NEED, iz da burny choppa. Iz one of da few gud skull crakking, meat choppin wepons we got. All da odas are weak as grots or dunt funkion rite (a.k.a broken melee animations). Trustt in Mork. Trustt in Gork. Trustt in Burny Choppa.
COS ITS BURNY, YA GROT! It has a fire damage mod on it, which helps reduce the number of successful hits you'd need to down someone and is great for finishing off low health enemies that are attempting to evade or get into cover. (Also good for quickkly finishing off downed enemies that you dont have time to fully execute). Cant comment too much on its use for a slugga boy loadout as I tend not to use the class that much, but im loving it on the Stormboy. Get in, hit hard, and if the situation is getting too hot you can always bug out and let the fire debuff kill or weaken the enemy for the next attack.
This has actually bit me in the arse before, I assumed it was a friendly because Orks use choppa blades right? Chain weapon means friendly marine! I was incorrect.
Datz why ya shud always be suspishus! Give da boy a shot jus fer sneakin' about! Chances are e'z a Deffskull tryin ta get 'iz grubby 'andz on yer kit!