From SRD
https://www.d20srd.org/srd/variant/clas ... lasses.htm
To start, Sneak Attack +1d6 is essentially = 1 Feat.Fighter
Some fighters prefer stealth and cunning over martial skill. This variant can also be combined with the thug variant.
Gain
Sneak attack (as rogue).
Lose
Bonus feats.
I'd rather have it scale with level or even do Precision damage based on the sum result of a Reflex or Stealth skill roll similar to the Diamond Mind maneuvers, but whatever. It is what it is.
Fighter basics: 1d10 HP each level (rounded median: 6), 2 SP, 1:1 BAB, Fort save
Rogue basics: 1d6 HP each level (rounded median: 4), 8 SP, 3:4 BAB, Ref save
So, extrapolated from these numbers, which are bull anyway since Rogues could virtually have only 1 HP between levels 1-20 and probably still survive given their combat-avoidance abilities:
• +1 HP per level is equal to the Improved Toughness feat, otherwise known as "The Real Toughness". Yes, this is a bad comparison since it only accounts for the first level of Fighter, as if they had 6 extra feats at level 1 and then NONE extra from 2-20.
• Rogues get more Chassis Basics than Fighters, due to the total between Fighter's 6 HP + only 2 Skill Points (8) vs. Rogue's 4 HP + 8 SP (12).
• Improving BAB 3/4 into 1/1 is most likely worth "One More Good Save Progression", unless I really should take all of these per-level values in sum rather than stating this is a feat, that is a feat, that is not a feat.
Anyway, averaged out, you get some kind of hybrid like d8 HD, 6 SP, and either 3/4 BAB and 2 good saves or 1/1 BAB and only 1 good saves. Pretty much... a Bard or Monk with Feats every level.
If Feats could grant caster levels and slots, you'd pretty much have the customizable hybrid of every class in 3e that Ever Was, Is, or Will be.