So this houserule increases the temptation of the darkside for light force users, potentially making the force more reliable and making Paragon a little less inevitable.
When a lightside force user rolls force dice, the entire pool is available, but any dark pips rolled WILL generate conflict... unless you take 1 strain per pip to resist the darkside, removing those pips from the force roll. (Or use a destiny point to use all pips with no conflict penalty)
Someone who has fallen to the dark side inverts the mechanic- When they roll Force dice, they must spend a strain OR WOUND to bend each light pip to their will, but get dark pips with only conflict. (Destiny point allows the use of all pips, with no strain or conflict penalty)
You may ALWAYS, of course, choose to roll LESS force dice than your force rating. At the end of each session, get d10 morality back as usual.
This makes the strongest force users the ones reveling in their power as they fall to darkness, which I feel is well represented in the lore, but may be an issue for short-run campaigns. The Fallen strain themselves to become the force's master, while the disciples of light must resist the darkness. And Once You enter the Dark Path, it is exceptionally difficult to reverse your Destiny.