Sounds similar to this,
I don't know if I because I am "old school" or got turned off of the multiple armors in Reach because of the credit system. I still like the system from Halo 3. Here are my thoughts.
1) Make the armors harder to earn and achievable only from ranking up to a certain point, not bought by credits if that system continues in some form.
2) Have armors that are only achievable by finishing campaign on different difficulties and/or time frames.
3) Offer an armor type to only those who achieve tough medals, such as a 15, 20, 25 kill Perfections would garnish you the premium armor and multiple "Headshot Honcho" medals would unlock a sniper variant.
4) Once an armor is achieved use your credits for the attachments, modifications, and effects.
I am not interested in putting a "war paint" om my armor, but a traditional military style camouflage that matches some of the environments might be rather cool. The idea of having armors harder to earn is based on a harder ranking system. I feel that you appreciate and feel more of a sense of accomplishment when the standards become tougher as you progress. I have a post called "Ranks you achieve during game play" that shows my thinking. I always want to hit whatever milestone was needed for the armor I wanted in Halo 3. Remember chasing down the original Recon armor? Reach offered so little challenge in this area that I quickly lost interest.
Was a post a few days ago.