This isnt true at all, marauder can only choose dps spec too.
And for the others trollign you know what he meant with magic damage (its kinetic and force dmg) and they do not bypass armor, but dodge and parry, (If you read the tooltip of armor it specifically says it reduces weap dmg, kinetic and force dmg too lol)
Oh and ....you ask for armor piercing internal dmg......INTERNAL DMG ALREADY BYPASS ARMOR DAMN GET INFORMED.
So no you dont know your class or game mechanic at all, this isnt a solo rpg but an mmo, get out of your shell and play with other player math prove MM is really good dps tree at higher gear level, once you achieve rakata gear, your dps will be much higher in MM than lethality. Lethality is really shine at lower gear level specifically because you dotn have armor pen talent. (the only armor pen you get is the accuracy over 100% that reduce defense, yes that include armor, meaning some armor pen)