Wow...Do you and I have a different take on PW and TWC or what?
You compare TWC with ambidexterity and PW w/o ambidexterity
First: there is some post (in the ole forums?) about PW with ambidexterity.
I admit I've never used PW as a combat style but I'd be shouting to blue heaven if a GM tried to apply an off-hand penalty for PW or required me to be ambidextrous to use the skill fully. My previous example did not apply off hand penalties for PW. (To be honest, the penalty did not even appear as a blip on my radar.)
Second: weapon bonus (material or workmanship) are added both to PW OB, TCW handle them seperately.
I didn't account for magical bonus or enhanced weapons in my example but OK.
weapon focus (ie fighter 5-lvl bonus) concern PW, i'm not sure if it'll be applied to TWC.
To me it's one in all in. If a GM applies the bonus to a combat style rather than an individual weapon then all combat bonuses would receive the style so TWC would get the +20 as well as the PW.
OK lets flesh out the example above. A 5th level fighter, max ranks in both styles and stat bonuses of (str +8, ag +8) using +15 weapons. (PW daggers, TWC hand axe and dagger.)
PW 18 ranks dagger (max) so PW is 12 ranks (12 x 1.5 =18 so max). OB = 54 (ranks) + 20 (fighter bonus) + 16 (stats) + 30 (weapon bonus) Total is 120.
TWC 18 ranks dagger, 18 ranks hand axe and 18 ranks TWC and ambidextrous. OB = 66 (ranks) + 20 (fighter bonus) + 16 (stats) + 15 (weapon bonus) Total is 117 for each attack. The difference is minimal for OB in the example above.
Take this out to a lvl 19 fighter.
PW OB = 90 (40 ranks max PW) + 30 (fighter bonus) + 16 (stats) +50 (Weapons are now +25 daggers) Total = 186
TWC OB = 110 (60 ranks) + 30 (fighter bonus) + 16 (stats) + 25 (Weapon bonus as above) Total = 181
In my opinion, the designers of both styles didn't want large differences in OB. What they were after was two styles that had different playability. That's why the main difference is:
PW one attack roll and bonus damage.
TWC one attack roll for each attack and 2 criticals.
If you want to roll one attack roll for TWC (or two rolls for PW) go for it, it's your game. Personally, I think it goes against the combat style design and penalises both styles but that's my decision for my game.
Nice talking to you