Jealous of the Miyabi, Chip!
That blend sounded delicious online, but I had to save a couple bucks and go with the Chiran shincha in my last order. Did the umami/sweetness last through multiple sessions, or just the low temperature steeps? I've found that I can usually get a little more umami out of the second or third steeping of the Chiran, oddly enough!
What were your brewing parameters [for the Kiri no Mori]? I haven't made any matcha for a long time, and the last stuff I had was not very good.
The Kiri no Mori is a very mellow, welcoming matcha. I've burnt it with hot water, drowned it in cold, and (just recently!) made it correctly, and it's always been smooth and tasty. But if you can whisk up a proper foam -- or happen to know someone who has the magic touch -- it's even better when it's thick and frothy.
My matcha making parameters aren't very precise, but I like to soak the chawan and chasen in warm water while I sift two medium chashaku scoops of matcha into a separate small cup. Once the water has boiled, I pour the lukewarm water out of my chawan and fill it with some boiling water to really warm the cup/soften the chasen. After all this, the water in my kettle is right around the correct temperature (185*); so I dry the chawan, pour in a tiny amount of water (2-4oz), and get to whisking!
Hope this helps!