I change my rockers every two years to meet smog.
I'm running a Crower special grind cam on my SBC Suburban. With the 1.5 Ratio rockers I get a lift at the valve of .447 int and exh (.298 lobe rise at the cam X the ratio). Just swapping out to the 1.6 rockers gives me .477 lift.) Because of the extra length on the stroke the duration changes slightly also.(A couple of Degrees I think) Bottom line is there is a slight but noticeable difference in performance. This is worth it to me to get a better pulling power but still have the option to go back to the smaller lift for smogging.
Hope this helps