JR Matchbox, Smart Fly equalizer are both viable options but really, why spend the money when your radio will do it for free?

Also, when you get into larger aerobatic designs most of us go to metal servo arms like Seacraft or SWB. Unlike a standard 4 prong plastic arm where you can center the servo and rotate the servo arm around until you find the place on the spline where it lines up 90 degrees, you're pretty much stuck with as close as you can get with a metal arm. This is where you get into needing sub trim for each servo get your linkage geometry correct. Your radio already does all this, just take the time to figure out how

Ahh twisted extensions...... yes there is no reason not to use them but for RC they don't provide any benefit, other than looks, they do look pretty

I know that places like Tail Dragger that sell heavy duty extensions made of 20g silicon wire, they twist them because they have no choice because that wire gauge isn't available in ribbon strips like 22g servo wire. But hey, if it makes you feel better, then it is better.