How do you best describe the rules you use?

I would disagree. The rule differences effects the setting. For example, Sir William, loyal servant to the Duke, was just made his heir and invested with the Duke’s bloodline, a Great bloodline.

In 2nd edition, Sir William would automatically receive the full benefits of this position (barring political.) He gains full access to his blood abilities and full access to his regency.

In 3.5, Sir William would not automatically receive the full benefits. He would 1st need to gain two levels of scion to access his blood abilities and score. In addition, to gain access to his regency he would need to ensure that his skill levels were high enough or else he would, again, only reach part of his potential.

2nd edition lead to divine ascension once you received your bloodscore. It was divine and inate.

BRCS, you need to learn to harnass and funnel that divine state.

Big difference in the setting. 2nd edition leads itself to farm boy ascending to King. BRCS leads itself to groomed heir ascends to King.

I wouldn’t actually agree that any of the above (while quite correct) is part of the setting. There is a definite mechanical difference (in BRCS you have to rise in level to fully tap your powers), but what does “level” mean in setting terms? The closest analogue is simply “power” - and in both cases, a “regent with powerful blood abilities” is still “powerful” by the nebulous in-game use of the phrase.

Remember also that NPCs don’t have to play by the same rules. If it suits a DM to have an NPC suddenly get the full benefit of his new investiture (adding as many levels as necessary), then so be it. Game balance only applies to PCs.

Indeed, from the perspective of the setting, there really aren’t any NPCs in 2nd edition that are low level and yet have great bloodlines. The fact that it was possible to do this as a PC can be viewed as a flaw in the rules rather than a feature, and that the BRCS “patch” fixes things to better reflect the intention of the setting.

Naturally that’s a subjective opinion, but it seems to be a valid position to hold.