oh and the current *basic* idealogy is 1skill=2cha (til the soft cap of a debated 110-120cha at 75)
This has changed. There's a nice influx of new research across several sites now that show this isn't quite correct.
Basically, in terms of magical accuracy, 1 Skill = 1 CHR when the difference in CHR between you and the mob is less than +10, otherwise 1 Skill = 2 CHR. ie: If the mob's CHR is 50 and your CHR is 60, you get the equavalent of +60 Skill. If the mob's chr is 50 and your chr is 80, you get the equavalent of +70 Skill.
The problem here is that you usually don't know what the CHR total on the mob (for every mob) is. Ironically, it seems that most common HNM (sky, kings, sea, etc) have a common cap around 120 for most stats - hince the magical 120 number (which, to note, is casually 'thrown out' for many things -not just brd- and generally respected, despite no real testing or evidence).
If you can read japanese and understand some pretty advanced number crunching like "Pearson chi-square goodness-of-fit" in statistics for obtaining 95% certainty, as well as record keeping of over 20,000 spells...you can find the info here: http://lodeguy.blog69.fc2.com/blog-category-17.html