Alright, I've read a bunch of the threads on this and realize first off that anything to do with a 4 armed PC is essentially "home brew."
So the question(s) I have are:
Kasatha race - 4 arms.
Multi-armed, 3 are considered off hand.
Multi-weapon fighting (MFW) replaces Two-weapon fighting (TWF).
Normally a person is at -6/-10/-10/-10/etc... for however many limbs they can attack with without any feats.
TFW - Normally, a person gets -4/-4. Reduced to -2/-2 with light weapon in offhand.
MWF - The three or more armed person gets -4/-4/-4/-4/etc.... -2/-2/-2/-2/-2/etc... with light weapon(s) offhand.
The "replace" I take to mean "uses this in place of" = is equivalent, but just for 3+ arms.
So then comes the problems with ITWF and GTWF: Do you get an attack with the off-hand weapon? Yeh, ok. But if they have 3 off-hand weapons, is it three more attacks (all at -5, so -2/-2/-2/-2/-2/-7/-7/-7). And then, of course there is GTWF - -2/-2/-2/-2/-7/-7/-7/-12/-12/-12.
I don't really see any reason not to run it this way, though it does kind of involve a bunch of dice rolling. Of course, RAW, there is no "IMWF" and "GMWF", so the argument would be that you'd only get one extra attack from each feat, so -2/-2/-2/-2/-7/-12. Which might also be fine.
I know I've read the threads where "THIS ISSUE HAS BEEN SETTLED" - LOL. But seriously, has it? If the RAI is clear that multi-armed persons are supposed to take feats (with less DEX NEEDED, I would add) that give off-hand additional attacks, it seems like all their off-hands would get said benefits. RAI.
Clearly RAW doesn't address this as I think they discovered real quick what a huge can of worms this is for their "5 attacks" attempted limit.
Keeping in mind that a character wouldn't get IMWF until BAB +6, it would mean +4/+4/+4/+4/+1/-1/-1/-1 at 6th level (earliest). BAB +11 for GMWF, meaning +9/+9/+9/+9/+6/+4/+4/+4/+1/-1/-1/-1... or something like that. 12 attacks at level 11, instead of a two armed person's 6. 3 main arm/normal BAB, and 9 for MWF, IMWF, GMWF. Really just 6 extra attacks because they have two extra arms which are each getting three extra attacks as off-hand. If you are inclined to limit it to MWF + 2 more attacks (for IGWF & GTWF), they end up with 8 attacks.
Also, if you added in the IMWF and GMWF feats, would you keep the DEX two points below, as MWF did compared to TWF?
Would you rule that ITWF and GTWF had "equivalent" feat versions as IMWF and GMWF? Yes? No? Why not? Again, I understand this falls into the "homebrew" realm a bit.
(ps. I realize that any ruling coupled with the PC getting Multiweapon mastery would be devastating as well - that would be the monster feat to "find" if I were a player with even just MWF)