Finley DaDum said:
Inertial Armor: +4 Armor Bonus nice but most useful only to classes that are not going to wear armor (nice but most useful only to monks, pretty much everyother class either has at least light armor or Mage Armor-maybe with the psionics above worth another LA +1)
This is good for most classes as it protects against incorporeal creatures whereas regular armor does not. It also allows combatant types to have quick mini-armor if they do not want to sleep in their heavier armor and since the manifester level is half the class level, it does go to AC +5 at level 6, AC +6 at level 10, etc. Not huge, but nice. Especially in situations where armor might not be the proper choice.
Finley DaDum said:
Spell Resistance: 5+Class Levels (so for a PC facing a spellcaster of equal ECL they have to role a whoping three to beat it-so basically useless for encounters where it really matters).
That's a 10% miss chance equivalent on all spells with spell resistance. This is obviously not as nice as the Drow 40%.
But, it is mostly good for fighting lower level spell casters (like NPC Henchmen). It is about equivalent to having +2 to +4 on saves against lower level mooks.
They also get darkvision which very few non plus LA races get (typically just Dwarves).
But, I agree the +6 to Dex is worth +1 by itself. With weapon finesse and a decent starting Dex, this is +3 more to hit, +3 more on Reflex saves, +3 more to Dex based skills, +3 more on AC (in addition to the Inerital Armor) and for many character concepts, adds about 16 to 18 to the point buy (if you use that).
Compared to Drow, they are similar. Not as good Darkvision or Spell Resistance, but very good Dex and no susceptibility to light.
With regard to the Githyanki, I think they are slightly less powerfu, but still similarly powered. Not so much in ability scores, but in special Psionic powers. Concealing Amorpha and Dimension Door are fairly nice, but they do not get the Inertial Armor.
However, still more potent than +1.