Backporting question

[Tanuki Tales]

I'm wondering how viable backporting/modifying some 5th edition rules into Pathfinder would be for balance.

I was thinking replace BaB and skill ranks entirely; characters get Proficiency equal to half their HD. This is split between full, half and quarter to match the old BaB progression, with full BaB classes getting normal iteratives. For skills they would pick X class skills (old Int+ skill per level) at level 1 and get their proficiency bonus on those skills.

I was also thinking anything that would apply less than a +4 bonus/-4 penalty to anything outside of ability scores would apply 5th edition's advantage/disadvantage system (changed to work on a 1:1 ratio).

Everything else would be the same. Thoughts?

[stack]

Big problem is that all the core math gets screwed up. AC is the big one; since full BAB lose up to 10 from their attack rolls, making iterative attacks worth much less. Low BAB types don't care since they are targeting touch AC anyhow. Skill DCs are thrown off too, though opposed checks wouldn't notice much.

Those are just the first things I thought of; fundamental system math shifts tend to echo throughout the game.

[Tanuki Tales]

Big problem is that all the core math gets screwed up. AC is the big one; since full BAB lose up to 10 from their attack rolls, making iterative attacks worth much less. Low BAB types don't care since they are targeting touch AC anyhow. Skill DCs are thrown off too, though opposed checks wouldn't notice much.

Those are just the first things I thought of; fundamental system math shifts tend to echo throughout the game.

AC is trivialized under the current system as soon as you start hitting level 8 though. This would extend the life expectancy of ACs in the 20-30 range and a melee beatstick with 30 Strength, 20 HD and a +5 weapon would only start seeing less than 50%/50% returns on the really "epic" monsters that have ACs in the 36+ range. I don't like the bounded accuracy as done in 5th edition, but combat rocket tag is just as bad. I also meant more "extra" than "iterative", sorry about that. So they'd get extra attacks at their normal proficiency.

DCs for skills generally range from 10 to 30. So we'd be looking at a range of results (from level 1 to 20) of a +8 to +23 for someone dedicated in that skill (before taking into account +4 and above bonuses). The bottom of that range is identical to the current system, while the end of the range still keeps DC 30s relevant, but more often attained then not.