Broadly speaking, I agree with you DAR.
The checklist does not have to be printed - it can be from memory it can (and often sensibly is) be from a menomic. BUT, it has to be correct and consistent.
My personal system is sort of modular - I have a folder of bits that I pick from (generic checklist, type information, avionics checks....) to build my kneeboard for a trip. What I've tended to do now I have a little instructional experience is to hand my version to a student (in reality a qualified pilot I'm refreshing or training onto a type), a copy of my system as applicable to that aeroplane and type of flying and invite them to do one of:
(a) use it, or
(b) use an alternative commercial or club checklist appropriate to type and role, or
(c) come up with their own checklist or system, and use that consistently.
I seem to end up with a mixture, but if they consistently get everything right in an appropriate order, I'm happy.
What can't be tolerated is no systematic method of doing checks, or checks done in a manner that doesn't allow me to confirm what they're doing (which so far when I challenge them has always shown they're being sloppy and missing stuff). What also can't be tolerated however is somebody who can't handle key actions (departure checks, approach checks, engine fire drills...) without referring to their printed checklist - some stuff needs to be in memory.
The majority of "grow up" pilots do tend to slip into using mnemonics or memory in the air and a printed checklist on the ground, but having some form of printed checklist available in the air in case of memory failure. I count myself into that category, along with most people I'd be happy flying in the back behind.
G