I think your math is a bit off. As hong points out, damage is more likely to be something like:
3.5*7 (sneak attack) + 3.5 (weapon) + 3.5 x2 (holy) +3 enhancement +2 strength. for an average of 40 damage on primary attacks, 38 on off-hand weapon. (Or maybe 34.5 if the character only has a single energy enhancement on his off-hand weapon instead of holy). Of course, +3 from bardsong or righteous wrath of the faithful isn't uncommon in a lot of games so we can make that 43-44 and 37-42. If you assume a three hits (a bit low in most circumstances if my experience is any indication since the character is getting 7 attacks including haste), the two weapon fighting rogue is going to trigger three fort saves.
Using your assumption of a +16 fort save, the character needs to roll a 14 to save on the primary attack and a 12 on the off-hand weapon. (with the initial 2 holy weapons, no morale, etc bonuses to damage). Since we're being generous to the fighter by assuming that he only gets hit three times, let's assume two primary hand hits (1st attack and haste) and one off-hand hit. His odds are 35%, 35%, and 45%. That adds up to a 5.5125% chance of making all three saves. Even if we are exceptionally generous and assume the lower damage numbers you posit which gives the fighter a 50% chance of a successful save his odds of making all three saves are only 12.5%.
That's why it's almost always a bad idea to scale a save DC on damage and allow it multiple times per round. The odds of making multiple successful saves go down exponentially.
As for the 100+ point attacker, that was a nod to what Hong refers to in the multiclass rogue section--as well as a demonstration of how just a few damage boosting abilities can stack to produce massive damage on a single hit. The character in question is a Shadowbane Inquisitor (Rog 2/Pal 5/Shadowbane Inquisitor 7) but could almost as easily have been the Rogue 4/Barbarian 10 from Hong's example. A lot of the massive damage comes from Rhino's Rush (a rather broken paladin spell that grants double damage on a charge attack), but even a mid sixty damage swing produces a situation where almost every creature is going to need a 20 to save.
That's why it's an especially bad idea to scale DCs with damage. Melee damage scales much faster than saving throws and there are lots of tricks that can be used to increase it.
Moon-Lancer said:
a normal 14 level rogue only does about 29 damage an attack. (7*3.5)+(2.5+3) They could do more they could do less. If your rogue character is doing 100 points of damage an attack, you have more problems then just this feat.
A fighter or any con based class is going to have a around a 16+d20 to thier fort save. they have about a 50% chance to make the save. I don't think the rogue is going to hit with every attack. I say the fighter has a 66%-77& chance he fails.