i think you would be best served to try the 4X before you buy one if possible, i have a fixed 4X one on my encore pistol, and from a rest at the range it is not to bad, but target acusition(sp) is really something else, everything moves around, your target and the background, this is my first experince with a ler scope and i wish i had gone with the 2X, btw i can relate to the tired old eyes, but everyone suggested i go with the 2X but i knew more than they did, i do like the idea of the varible, with my encore(7mm-08) the higher magnifacation may come in handy, atleast one of these days,

best of luck