I'd drop in a 17lb. spring. If all you're shooting is .22s, slide velocity won't be very high or unlocking very quick, so you don't need much mainspring. With .22s and light .45 loads, 1911s are very forgiving with respect to spring balance. If the mainspring is heavy enough to ignite primers, and the recoil spring isn't too heavy for the gun to cycle, you've got lots of margin for error. 17 lb. mainsprings will usually be heavy enough to bust primers reliably.
Spring balance on 1911s is widely misunderstood. As you noted, racking the slide is noticeably easier with the lighter mainspring. The same is true in shooting; heavier mainsprings slow unlocking, thereby reducing slide velocity. I've seen folks put outrageously heavy recoil springs in 1911s to "set them up" for heavy .45s or 10mms, and leave in light mainsprings. Wrong! My Ultra Aegis 9x23s have 25 lb. mainsprings with recoil spring assemblies for standard .45 Ultra Carries. They also have EGW flat-bottom firing pin stops. Slide unlocking is slowed by the heavy mainspring and flat-bottom stop, so heavy recoil springs are unnecessary. The magazine springs are also extra-strength, so the follower can keep up with the slide. With high-quality, properly fit hammers and sears, you can still get good triggers with heavy mainsprings. My Ultra Aegis guns have triggers right at 3.25 lbs.
Using lighter mainsprings to reduce trigger pulls isn't necessarily wrong, but one should realize what else is involved. If the hammer hooks are too long, or the hooks or sear are rough, the new, lighter trigger pull will feel creepy and gritty, and feeding function could suffer. No free lunch.
