Edited OP to clarify.
Those PrCls listed definitely suit martial arcanists, but don't necessarily have armored casting. For example, A Ftr4/Bard4/EK4 will be able to cast in armor just as easily as if he were just a Ftr6/Bard6, but he'll have more spells and a higher BAB.
Eventually, I may separate the inherently armored casting PrCls from the ones that merely facilitate being a martial arcanist...but some will be tricky, like the Enlightened Fist.
Take edk and abj champ OR take edk and using craft wondrous item, craft youself a robe that gives you AC.
Theres this non-wotc publication called 'Abjuration. Shielded by Sorcery' by Mongoose publishing. In it, theres a feat called Abujurative that gives you +4AC as a supernatural power and apprently, being an abjuration, is boosted by the abjurant champion.