This one is now 6 years old I bought it two years ago as a nursery seedling, I left a sacrifice on it but the low growth become a little weak so I cut it a month ago. It back budded quite well suprisingly. I will probably repot it next year in august like mugo.
Spring update:
The species seems to revert to juvenile foliage a bit more easily than other pines, but it should not be an issue, the juvenile needles mostly have fascicles under them.
Also I forgot to mention that I plucked the strong buds in august and the tree actually made a few microscopic buds at each cut site:
