Actually, 13. You took PTWF at 10.
Oh god, don't start with that particular bit of wrongheaded out of context nonsense. And pulling that one out after accusing me of being overly TO in this very thread for suggesting you purchase a domesticated creature to ride on? Really? Not too classy. But I'll just leave you with this quote from the "Feats" section of the PHB, on page 87:
"Acquiring Feats... members of some classes get bonus feats as class features. ... Prerequisites... Your character must have the indicated ability score, class feature, feat, skill, base attack bonus, or other quality designated in order to select or use that feat."
And I'll ask that when you try to bring up out of context quotes from the Monster Manual, you make note of which sections you got those quotes from, and why you think that section applies to class bonus feats (as opposed to just racial bonus feats). The PHB was specifically talking about class bonus feats, you see.
There are also various class independent methods, though only the half damage one works on Fortification armor.
So, when I said that other than the half damage one (which really hurts) you're screwed and you said there were "many" ways around that, by "many" what you meant was "none." Gotcha.
But really, you're a beatstick at high levels. If you only start slacking at 15+, you did a fucking amazing job on your character. And before that you don't encounter Heavy Fort (creature type immunity I've already discussed the bypass methods for).
People have talked about giving a fortification style effect to heavy armor. So, you'd be seeing a heck of a lot of it at lower levels, thus leaving you horribly gimped. It would just add one more to the list of "stuff that makes Rogues suck." Also, this thread is talking about balancing. Saying "whoops, we screwed another class at higher levels even more" tells you the method isn't going to work. Me, I'd have no problem with just giving Light Fortification to Medium Armor and Medium Fortification to Heavy Armor (with the enchantment getting you the rest of the way there) but allowing sneak attacks to bypass that entirely (so it only stops critical hits). That way these armor types get much better (and Mithral isn't so amazing) but Rogues are less screwed.
Who cares about Rogue's gimped cousins and some random not updated 3rd edition class?
People who care about balance, which was the very point of this entire exercise to begin with. Did you fail to get the memo?
JaronK