
Incarna i20 used a “Lore System” initially for specific knowledge of species, places, events, groups, etc. This just added levels to the History Check, and the GM increased the DC of ANY check that was not related to the context of where the character had their upbringing or was studied as part of their education, background, or class. Weapon attacks and most other skills were left intact. The initial run of i20 for 2025 replaced the entire d20 Skill System with the i20 one – All new skills as reflected in the iCore rules were used, and skill levels are used. Weapons still used PB. With the “final cut” of 2025 Skill System, skill levels of familiar weapon groups were tested. It makes the entire set of actions skill based, unifying it. PB is used solely for saving throws and ability checks directly. PB is pretty flat, rarely changes and is useful for generic checks, but specific activities should be governed by their actual familiarity and specific skill. Once again, going more in the direction of classic iCore Incarna. After careful consideration, the familiarity rules will stick in the final cut, but PB will be used for weapons as well. Otherwise wizards could be better at fighting than fighters if they wanted to throw all their CP at it, violating game balance (though the reality of it is appealing). The system is heavily balanced with the nerfed numbers of PB.
Conclusion/Summary: Combat, Saves, RAW Ability Checks = Proficiency Bonus; Other Skills = CP level
It only seriously impacts the game if the type of play is heavily knowledge and skill based, and not based on combat emphasis.