[Bruno]

I'm pretty tired so words sense make may not.

When splitting Per and Will out of Int, I base Initiative off (DX + Per) / 2, giving initiative scores that average around 10.00 rather than 5.00. Combat Reflexes gives +1 to Initiative.

If I were to play with random initiative, I would do it with the base initiative on this scale, plus 1d6. IE, the static part would be the biggest influence; the random part would be important, but not overwhelming like it is in D&D-style systems (until you get to high levels). This lets things shuffle around enough to keep things fresh without taking it too far from how the GURPS rules expect things to be acting.

If you're using Basic Speed for initiative, the equivalent would be 1d6/2 but that's nasty IMO. It's better to base Initiative on Basic Speed x 2 + 1d6.