I bought a GP100 a few months back, which is the SP101's full-size brother. I found the trigger pull to be objectionably rough (but acceptably heavy) when I first got it home. But over the past few months, with about 1500 rds. and a few thousand dry fire reps, it has smoothed out considerably.
I'm not really familiar with the SP101, but if your concern is more with the smoothness of the trigger pull, rather than the weight, then I am not sure revised springs will help that much. But I would strongly concur with the advice about dry firing it. Plus, unlike some other revolver makers, Ruger's attitude on dry firing is basically, go for it. To me, that says something about the reliability of their products.