I like it.... use it.
If you need to modify it do so, but don't make it longer.This is a RV not a B737 two crew transport. It's a nice size now...
Personally I use flow top to bottom, front to back, CIGARS, Lights/Camera/Action, GUMPS and Aviate/Navigate/Communicate.
Emergency committed to memory and reviewed the before you fly first flight of day. T/O brief to self out loud normal and IF engine failure early or late (plan, speeds).
I'd recommend using it as a CHECK list not a DO list. Each item look, take a beat and respond. I say that because there can be an expectancy where you see what you want. Ask me how I know... Don't ask
Before Start - Personally I would find more value AFTER start, oil pressure and LEAN the HECK out of it for taxi.... Pilots wounder why they have fouled plugs and have lead deposited. All taxi should be lean.... Should you enrich for run-up? No not really, may be a little, but also consider high density altitude and lean for max RPM.
PS After Shut Down- You say all switches off than later flaps up. Likely not going to work. I bring flaps up after landing clear of runway. Frankly I would skip the After Shut Down section, but it is your check list. Do you really need to be told to put headset away? I think it is fine; just not my opinion.
Before shut down I may do a short runup and lean to miss. Then I shut down. You should see an RPM rise. Bottom line it cleans the plugs out.
The after-take off, en-route, descent.... some of this is normal procedures and should be memorized or Mnemonics... head out of cockpit, but no criticism; if this helps you. Not sure if you have EFIS or avionics with checklist, consider going paperless.
Mnemonics
CIGARS - Controls (free correct), Instruments (Baro Compass correct), Gas (tank as desired), Attitude (Trim), Run Up (Engine Inst, mixture as Req, L&R ignition, Prop exercise), Safety (belts, canopy, T/O brief)
Taking Runway - Lights/Camera/Action - Lights (self explanatory), Camera (transponder), Action (T/O clearance or call departure, flow "L" or "?" pattern: canopy, mixture, boost, flap trim)
GUMPS - Gas (tank as desired + pump), Undercarriage (Gear down & welded/ Flaps), Mixture (rich or as needed for high density Alt, Prop (High RPM), Safety (Belts, lights, pray
After landing - Flaps up, Transponder off, LEAN mixture - (Routine normal procedure by memory and flow pattern)
AVIATE, NAVIGATE, COMMUNICATE - For any emergency or flight regime, commit to memory speeds.
TURN, TIME, TRANSITION, TWIST, TALK - IFR transition IAF, FAF