Bhante- Welcome to the forum. The great thing about home roasting is how you can tune it to your own tastes. Personally I enjoy the large variety of tastes from single origin coffees roasted for espresso, I very rarely go past the first few pops of second, and think sourness is avoided by having a nice long stretch from 1st to 2nd crack.
20 years! What machine do you use?
I do not care to speculate on the caffeine content of a ristretto. Until the Caffeine Mojo Pocket chromatograph comes to market I think we are just guessing.