Reversal of Polarity
There are alot of alternate methods. I use
Die Roll + OCV >= 10 + DCV
It's symmetric (easy to remember) and there's no subtraction (microseconds slower than addition).
You can use the fact that the bell curve for probabilities on 3d6 is symmetric to "reverse the polarity" on all your die rolls. The chance to roll a number N or less is equal to the probability to roll the number, twenty-one minus N, or more.
P(N-)=P((21-N)+)
For example, P(3-)=P(18+) only one chance in 216 rolling the 3 or rolling the 18. Likewise, P(18-)=P(3+), 100%, any roll you make is going to be 18 or less as well as 3 or greater. In the middle, P(10-) is 1/2, half the rolls are 10 or less, and P(11+) again 1/2, half the rolls are 11 or more.
That's where the formula for the "to hit" roll above comes from. Normally,
Die Roll <= 11 + OCV - DCV
but that probability is the same as
Die Roll >= 21 - (11 + OCV - DCV)
Die Roll >= 10 - OCV + DCV
Die Roll + OCV >= 10 + DCV
This form also has the advantage of being virtually the same as the 3000 lb gorilla's BAB(OCV) and AC(DCV), so it may ease the strain of redocrination of players imported from the jungles of Deetwentie.
You can reverse the polarity for all you rolls in Hero using the symmetry rule P(N-)=P((21-N)+). The familiar 8-, 11-, 14- become the slightly strange 13+, 10+, 7+. For skill checks, the ease of use gets a bit gummy (unless you are coming from D20 in which case it is pretty natural).
Normally,
Die Roll <= 9 + CHAR/5 + Levels
so using P(N-)=P((21-N)+)
Die Roll >= 21 - (9 + CHAR/5 + Levels)
Die Roll + (CHAR/5 + Levels) >= 12
So add your levels and your innate ability to do the skill to your 3d6 roll and beat a 12. The GM can adjust the difficulty of the task up or down, by either giving you a bonus or penalty to your roll or moving the target number 12 up or down. A Familiarity is a 8- or 13+, so Die Roll -1 >= 12.
The only place where reversing the polarity becomes more trouble than its worth, is when you have skills with critical checks, ie you need a 12- to make the skill roll normally but special benefits ensue if you get 6-. The rather arcane formula for this condition is (someone check my math here):
Die Roll + (CHAR/5 + Levels)/2 >= 16.5
So a total reversal of polarity does have some pitfalls.
EDIT: What Intrope said. I am a slow typer.