again, I hate to bring down the average intelligence level of this thread with my own brand of dim-wittedness, but...
is toughness a feat-tax too? Isn't it in the "must have" range of feats?
Toughness is a nice feat, but it has nowhere near the power level of epic-tier Expertise (epic tier being where Expertise grants +3, which is the point where it becomes ridiculously overpowered).
Toughness represents at most a 28% increase in HP (L1 Wizard, 8 Con, no HP boosting background), but by level 2 that drops to 23%, and the percentage continues to drop as the character levels, with spikes at level 11 (17%) and 21 (15%). By level 30, it's only an 11% increase in HP. This is a somewhat unrealistic but best case for Toughness.
By Epic tier, a highly optimized character without Expertise can be hitting an on-level skirmisher 75% of the time (20 starting stat bumped every level, Fighter/Rogue weapon talent, +3 proficiency weapon, Kensei, stat-boosting Epic Destiny, +5 weapon at level 21). In this worst case scenario for the power level of Expertise, +3 to hit represents a 20% increase in the character's offense. Put this character at level 30 (with a +6 weapon), and the percentage increase is 23%.
So, in a worst case for Expertise and best case for Toughness, Expertise is still a significantly larger boost to a character's offense than Toughness is a boost to character's durability, except for a couple of levels at the start of a character's career.
If you consider more "average" cases, the comparison is even more lopsided. That is, for a L1 striker/leader with 25 base HP, Toughness is a 20% gain (13% at 11, 12% at 21, 9% at 30), while for a character who starts with an 18, uses a +3 proficiency weapon, takes a stat-boosting epic destiny, and already has a +5 weapon at L21, Expertise is a 25% boost (30% at level 30).
And this doesn't address the concept that character offense is more important than character defense, or that Expertise has a more comprehensive effect on offense than Toughness has on durability.
So, no, I wouldn't consider Toughness to be at "must-have" power level (or more accurately, I don't consider Toughness to be overpowered, let alone ridiculously overpowered).
t~