I've recently switched from clarinet to mellophone (F I think) for next year and have been playing it with a 29D mouthpiece (it's a french horn mouthpiece with some sort of adapter and was branded by the lip). Some of the coating is rubbing off so I'm looking into getting a new mouthpiece, preferably one that will help me develop my embechoure and allow me to hit some higher notes. As of now, I'm looking at a Bach 12, but I also want something unique like a colored Kelly 6V. What do you guys think?

The 29D mouthpiece is fine (except for the wearing off of course). No "mouthpiece" will develop your embouchre only long tones, scales, and fexibility exercises will do that. A bach 12 is acceptable. If you want the Kelly mouthpiece (and there are lots of positive reasons to get one) the 6V is just fine. The 6V is patterned after the Farcus mouthpiece and then Kelly did some stuff to make it perfect for the mellophone. If you are going to be marching get a color that matches or goes with your marching uniform.

Thanks for the advice! I think I'll go with a black Kelly 6V, seeing as how it's literally half the price of a Bach 12 and it matches my school colors (black and gold).

<Added>

After bringing this up with with some friends, they've also decided to get black mouthpieces.

Or you could alternate. Black, gold, black ,gold and on down the line.

well, there's only one other mello so that probably wouldn't work

<Added>

I finally settled on a black Kelly medium cup french horn mouthpiece which I will use with an adapter