If you try it, be careful! Make the change, then carefully test to see if it's really what you want.
Spring and damping rates can make or break a car's ride, handling, and possibly safety. Those of us who mess around with older cars and trucks tend to swap springs and such around pretty casually, but it took a lot of engineering to get reasonable load capacity, ride, handling, etc in that set of springs and shocks under a wide variety of situations. If you go outside the factory ranges, you're on your own. Think about the race teams that are constantly adjusting and testing ...
Removing or adding leaves is one way of adjusting spring rates that is both low-cost and reversible. If the truck is not used for hauling much weight anymore, you might get away with it. Beware that your existing shocks' damping properties may not match up as well with the now less-stiff springs.
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they'll still ride fine afterwards
Ride quality is a very subjective thing.
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no ill effects
Probably no permanent effects, if that's what they mean. If you happened on a serious mismatch, you could experience excessive sway, harshness, hitting the stops, oscillations, and other weirdness in handling could put your truck into a tree - and that can be a very ill effect.
Be careful!