I'm not nearly smart enough to contribute to the electronics design part of this. But, one thing I've always wanted as a costumer was for the portion of the display in the chest to be very minimal. Just a small board with the LEDs on it. Then have a cable that runs down to, say, the belt pouches, where the main board would be. Then the board could be in a project box, rather than just loose.
I've had chest lights get damaged by sweat, plus I always welcome smaller components in the suit.
I forget who made mine, but it's 2 boards connected by a ribbon cable. Not exactly my dream setup, but close 
