As Im reading into the Magus and planning to go Dancing Dervish I noticed that with a high enough Dex. you start to lose some Dex bonus at high levels if you go with better armor. I know preferably you dont want to waste any AC so I thought about a 3 level Dip into fighter to get the Armor Training +1. This would reduce the AC Pen by 1 and increase the Dex by 1. Throw in Mithril which drops AC Pen by 3 and increases the Dex by 2... You could potentially wear Mithril Breastplate which is +6 Aromor with a +6 Dex Bonus and no AC Pen. You would still have 6th level Magus spells, but would lose one Magus Arcana, the Greater Spell access and the True Magus... However you would gain 3 Fighter Feats. Would this trade off be worth it? Im not familiar with the way the Magus is played so Im not sure how important those last 3 caster lvls would be. Chances are our game won't get that high, but incase it does I always plan for end game. (who doesn't) Thanks for tips and advice!
Sounds extremely valid to me. It means you'll be more of a fighter than a caster with those extra feats and lower casting level, but if you're going Dancing Dervish it sounds like you were planning on doing that anyway. Besides, a Magus's specialty is casting offensive spells in melee, so better armor and more feats won't hurt you at all.
The Myrmidarch Magus gets Armor training at level 8 as Class Feature, also gets Armor Training 2 at level 14.