I have experience with both peat and coco pellets (pucks) and I’ve tried their bricks in Sea of green also. While I think it has its advantages (can be use without pots, easy decomposition) I don’t use them anymore. The single reason is the are too wet (especially peat version). It is too wet for “set&forget” germinating for seeds and I think it is too wet for cloning also. When you compare it to rockwool, rockwool dries out much faster (so fast that on the other hand for bigger clones - 20+ cm high - it is needed to use 4cm cubes not 2,5cm ones otherwise you need to water them two times per day).
That jiffy’s too high humidity when inserting clone without roots can’t be easily solved because I still need to have clones enclosed under a dome to decrease need for perspiration.
That is just my personal experience and maybe I’m too used to maintain cuttings in rockwool (and add humidity using spraying every day to dome). I know it is perfectly doable in Jiffy too, because I’ve seen many growers use it exclusively - for example Breeder Steve.
Maybe someone will vouch for Jiffy, but I can’t - I’ve got much better survival and rooting rates in rockwool cubes.
On the other hand bigger rooted clones really thrive in Jiffy, in this case humidity is absolutely in proper level.
I’d try only strong bigger cuttings in jiffy. Controlling the humidity and use partly dried out pellets (or at least letting water drain out as much as possible after expanding puck), adding only enough water to soak only bottom of pellets. Temps 24-25 Celsius works best.
If it is still too humid, I’d experiment with having dome off part of the time. Good luck!