10/12% is about our yield on popcorn and sweet trim, so you are probably on track there. The dry sieve kif that we make tastes more floral than the oil we make too, as more of the terpenes are still present, so no surprises there either.
We've run kif in the Terpenator, but never the Lil Terp, so I don't have a direct comparison for you. What we've found running the Lil Terp, which operates identically to the Tamisium, is that it doesn't recover very well below 110F, and because of the vacuum pumps, we can dial down the Terpenators to 75F, so as to yield higher THCA and produce shatter.
On the other hand, the Lil Terp is small enough to fit in our chest freezer, which opens up opportunities extracting fresh frozen material, so it is a question of the best tool for a job.
The issue with running kif in a passive system, might be getting flow through such a densly packed medium, using just gravity, so you might consider mixing it with something adding porosity.
The other issue of course, is that the solvent that you are soaking the kif with in a passive system, is already partially saturated, so unlike the Terpenator which flushes with clean butane each time, you will have to make a second run with the Tamisium or Lil Terp, to flush out the remaining oil.