I'd absolutely like to be able to customize color and ideally font. As I said in another thread the way I'd do it if I were God of the Devs would be to have color, font, and placement defined in an XML file. If someone on the dev team gets bored they can make an in-game UI for customizing, but a fan will inevitably slap together a UI in C# or Java or whatever as a standalone little app.
As for the second poll question you're gonna have to talk a little more about what you mean by "mature" and "realistic." Given that the current UI isn't exactly Baby's First Warmachine brought to you by Fisher Price, and Battlemechs don't really exist, your intent isn't obvious.
Do you mean that you want the HUD to be replaced by in-game elements either in or emanating from the cockpit? Assuming so, are you familiar with the (American) F-35, joint strike fighter? The pilot's helmet looks like this:

Those horn looking bits are laser projector doohickies to put the HUD on the visor of the helmet. It does crazy stuff like indication the position of enemies through the body of the aircraft. What I'm getting at is that the devs could toss a curved "this is totally a helmet display" effect a la Metroid Prime onto the existing HUD and call it a day, and we'd have a more immerse UI.
Edited by Blue Footed Booby, 21 April 2013 - 08:04 AM.