What are your thoughts on a pure caster in light armor without the proficiency feat? I have augments and enhancements to overcome the spell fail chance and it appears the only other downside is -4 to skills, which seems a worthwhile trade-off for the improved AC, fort and other bonuses that come with good armor. The other factor, at least at my current mid levels, is a dearth of decent robes. Perhaps that changes closer to cap.
At least the PRR bonus of armor requires the proficiency, not sure if any other bonuses do. I have a Bladeforged Sorc who has the Adamantine Body feat, don’t play him much. Rereading the Wiki though, as the PRR you get for armor is based on BAB, I’m not sure it is actually helping me all that much though…
One more thing. The problem I’ve found with my Warlock is that Named armor is geared to the standard class usage thereof. Outfits are Monky. Robes are castery. Light armor is designed for a dex based ranger/rogue. etc. The worst example of this is the RL gear. The LTS is probably the best example of armor that is somewhat against type, but only somewhat. So if your ideal end game armor for caster affects is only on a Robe, then being able to wear L Armor isn’t going to get you much.