The "balance" means that if the mainspring is heavier than the rebound spring will allow, it is out of balance and the trigger will not return.

The kits like the Miculek and Wilson Combat mainspring-rebound spring kits are meant for guns that will also be tuned up, have the wear surfaces polished and stoned, and the friction reduced.

I lubed up some of my revolvers with moly, and it slicked them up pretty good. Moly penetrates the pores of the metal, and reduces friction and will allow lighter springs to work better.

In my experience, I am not a good enough shot to really see any benefit from slicking up my revolvers. I have a bone stock Ruger Speed Six that I shoot better than some of my S&W's that have been "worked". My slicked up 10-14 shoots marginally better than my police trade in 64-7 which has heavy springs.

What was said by scooter is true, the gun may jam up with live rounds but work fine in dry fire. I put light springs in a DAO 10-10, worked fine with no rounds in it, took it to the range and the first shot jammed the gun up......the firing pin got stuck in the primer and the lighter rebound spring didn't have the force needed to return it. I put the stock springs back in and it worked 100%.

Overall, decide how important a little bit of a lighter DA and SA pull is to you and how much you will actually benefit from it. We all like to tinker, but I have learned that if it works with the stock springs, I usually just leave it alone. Unless you're shooting in matches like PPC or Bullseye and need a slick DA pull or ultra light SA break to take 1/4" off your groups, it won't be the night and day difference you may expect.