my .02.
i started with drymistat tubes, working for that 70/70 target. i got maybe 8 or 10 tubes since i had multiple humidors going because i thought 40 count meant 40 count, and when you go a little overboard with auctions and weekly shipping, you just get another humidor. also it was super easy to get packages that included humidors. that changed when i got a small fridge that i was gonna make into a wineador. for that i used the old jars/tubes, and added KL since it was a much large volume to humidify. it wasnt thermo electeric, and my room got super hot in the summer, so that caused me to experiment/play around/constantly monitor it for the whole summer and just became a serious PITA. it got easier in fall, but i had to again monitor it a sh*t load, so again, PITA.
during this time i started to read the forums more, started trying (and really liking) the smokes that cost more then i what i looked at. so instead of searching for 1$ bid stuff, my auction habits changed, and the humidor investment increased. having more investment in the stogies made me more irritated with temp swings, humidity swings, and sub par smokes when i got around to it. so for peace of mind, a thermo winedor project became a birthday gift to myself. solved my temp issues and after drawers got seasoned, it would be around 70% with a baking sheet of KL at the bottom, another nylon/aquarium media bag in a top drawer and a tube or 2 per drawer. probably over kill, but checking them has been a habit ever since i moved on up from the cigar storage bags i started with. not a bad set up, but i would notice some cigars would not like it around 70 (which could climb up to 72 at times). for those cigars, they are in a diffrent tray, with a 65% boveda packet on top (been in there for about 7 months now, with no sign of shrinkage or need to be replaced. this became my super cheap insurance policy to try and keep the rh more consistent. and it has worked this has keep the top end of the wineador RH around 65-66, and the bottom around 67-68. if i doubt the hygros, i swap them out with one another and they do register the change. i understand that i probably have some overkill steps, but i use all the extra jars and tube and have to infrequently add DW to them until the winter, and i did not find a purpose in throwing out perfectly good stuff.
so the KL works, and as long as you follow the instructions on it around many pages here, it will keep you near 70RH (i think i used this, but it was long since tossed "exqusicat fragrance free) . BUT if thats not what you want, then your quite hard pressed to drop it lower. i had played with ways that got me somewhere i am happy, and dont mind the upkeep. when space will get tight, heartfelt 65% will be my way to go, and if some cigars are a little wet in that range, then i will segregate them with a 62 or 58 boveda around them.
if i were to start all over, then i wouldn't waste time with KL. for the amount of surface area i needed to get what i wanted, i used a good deal of space, and had a lot more guess and check work. not epic, but not always possible. if you want an easy, smart and safe bet, heartfelt is the way go man. and thats coming from someone who has not used it yet.