Here's what I posted about these two drums in another thread on these 2 drums...
Tons of difference between the Supra and the BB, but either drum sounds great.
For the 6.5 size, which I have experience with...
The brass shell on the BB makes it a smoother, and more solid sounding drum to my ear starting with an un-muffled drum.
With Moon gel or something like that, the "solid" qualities can be pretty equal, and the sound that naturally occurs because of the material used is the difference.
The "ring" on the Supra (I think anyway) is more of an "open spread" and it kinda sounds a little more hollow--kinda like a 'thonk"--and that's NOT in a bad way, or a bad thing, just how I can describe it.
The BB has more of just a crack and the 'thonk' if you want to tune to get that, is a little brighter.
I don't think the BB's brass shell lends itself to the same type of character as the Supra.
When you really start to know drums, and can pick out things that make you think, "that's probably a brass drum", or," that's probably a deep wood snare" when you hear a Supra, you know it's a Supra (and a lot of people here would probably say the same thing).
It's in a class, and has a sound all it's own.
The BB is a plain fantastic drum.
Great sound, records great and (IME) is ready to record very quickly.
I find it a bit louder of a drum as well, compared to the Hammered 6.5 Supra I own.
BB's (IME) are very consistent drum to drum as well.
I own a '00 and a '04 BB, and even though the actual shells have a slight difference in tone, the overall sound of the drum when tuned up is virtually identical side by side.
I have 2 of the same drum because if I'm on a gig, and one goes down, I have the same exact sound and quality in my "back up".
But, if you wanted more "character" from a snare--in an either/or situation--a 402 Supra may be a better choice--if you like to fly wide open and get some cool overtones, and some nice hardy ring from the drum--something like John Bonham got on some of the Zeppelin stuff.
For that kind of thing, I think the 402 is in it's own class.
I go for the 6.5 size myself, but the 5" Supra is a great sounding drum period, and if you only had one of those snare drums---ever--you'd be in pretty darn good shape in any situation IMO.
......
You can change things on the 2 drums for different types of sound, like 42 strand wires, different types of heads, but the great thing is that each will sound good no matter what head you put on it (unless you tune it like crap--but even then it still sounds better than a lesser snare...).
Since both drums sound good, the extra money for the BB would be up to you, but it's not just as simple as "Do I want a Black drum or not" between the 402 Supra and a BB.
If you want a Chrome plated drum (but you like the sound of the BB over the 402), you could get a 6.5 Brass Edition snare, and the sound would be the same as the BB, but different than the regular 402.
Hope this can help.