Nice Atropurpureums, traveller!
Some of the Woody Dwarves call them “Bloodgoods”.
I would let them grow. Wire them into visually pleasing shapes while the trunks “get swol”.
You say you’d like to propagate them.. I’d wait until after full-spring “push” and take some cuttings IF i was going to trim them at all. (I personally would just let them grow, worry about cuttings next season)
Are you familiar with propagation via stem cutting? (There are many resources available here, in the Tiny Forest)
Pleasure to make your acquaintance.