Why shorter? Shorter boards will turn easier and tighter, period.
So you want to step down from the 8’6”, (btw – rounded pin- looks like a nice shape – naming conventions are retarded – to me looks like a short hp lb, whatever) and you want to do turns and tricks…..OK.
For the first transition, the 6’8-10” might be the logical step. It will turn better than the 8’6” and float you in the winter. Once you get the 6’8” dialed in, you’ll probably want to go shorter to further refine your technique.
As others have said you’ll want a couple of boards for varying conditions so keep the old boards. A short fat board (6’ or less), lets you have fun surfing (turns etc) knee to thigh/waist waves in a way that a longer board simply will not. A slightly longer board, 6’6-10” will get you into the waist/chest/headhigh waves easier. The 8’6 looks great for bigger long period waves. Different waves, different boards.
You’re trying to figure things out, welcome to the club. Others on the board will crow about their fav board and advise going shorter, etc. these folks have figured things out for themselves. Eventually you will too. Relax. People surf for a long time, as they evolve- so do the boards they surf. Good luck.