Disclosure: Admitting up front that I have never used the Boveda Humidi-Paks. I got scared off by the early stories of leakage and damage, and could never give them a real try. I also saw first hand what happened when a pack leaked in a friend's case. What a mess including a case that could not be salvaged! (I still have an old Humid-Pak version on the shelf unused and unopened, a door prize from a long ago Road Show).
Instead, my choice is water beads from an arts & crafts store inside a perforated soap dish or prescription bottles. These containers are usually in the accessory box inside the case and last about 4X as long as a dampened sponge. I've never had had any leaks or problems with them, and all my wood guitars and ukulele show no signs of humidity issues. Dampened sponges have to be re-wet every week or so, but water beads can last a month and still not be fully shrunken or dried out. (The beads start out at ~3/8" diameter and shrink to ~1/8" or BB size when dry). If starting with a very dry case and guitar, I often put the empty case -- repeat no guitar -- sitting propped open in the bathroom during a steamy shower to "pre-charge" the fabric and padding, and maybe the plywood too. The case can absorb a LOT of moisture until you reach equilibrium with the house interior, and will quickly dry out any humidifying devices at first.
When we lived in Alaska, we struggled mightily -- almost ten gallons a day through a cabinet humidifier -- to get the house up to 20% RH during the winter. Here in Idaho the weather is not as extreme, and our house usually bottoms out at 37% RH, according to both of my hygrometers. Summer conditions are fine in both states.
Whatever works for you is fine. Just telling my tale.
