I didn't buy greens, but I did buy heavier springs to swap into my blues.
It worked out quite well for me. I didn't think blues were too light necessarily, and I still have a board with them, but I really enjoy my greens as well. I did already know I liked heavy switches (stock clears).
60g Korean springs won't be any heavier than blues. I personally can't feel a difference up until 67/68g, which is already halfway to the weight of greens. I personally went a bit heavier than stock greens, with 85g sprit springs.
Just keep in mind that it will take you a bit of time to get used to the heavier springs, and they may feel too heavy for a while. I'd say give it a week or two with the heavier springs before you pass judgement. It took me about a week to get used to my clears, coming from only having used blues and browns.