You're right, pine is slow (and you're not the only one thinking about age). You may be able to find more developed but young J. and Scots pines at Meehan's Miniatures in MD. Describe your vision to Ms. Meehan and ask for recommendations. I have nothing against VA pines except they are so slow...
FWIW, I collected several native sweetgums over a few years. I cannot get them to survive. The root balls are coarse and woody. Maybe taproot?
I have one in the ground, maybe 7 years, which was container grown by our Dept of Natural Resources for reforestation. I've been cutting the roots every...
I bought a decent small white chojubai from International Bonsai's yearly catalog of plants a couple of year's ago. Price reasonable. Make sure to check when the catalog is available.
Hi, I have the same thing frequently on my J. Maples. The leaves just get beat up. I don't know why but they remain vigorous to this day. (They are in morning sun about 4 hours and dappled shade the rest of the day.)
The root maker pots, with all the holes, may be drying out too fast?