I am actually a bit surprised that this thread has lasted for so long!
When I instructed in light aircraft, I issued students with a checklist, but required them to learn and perform checks from memory (using a mnemonic checklist) while flying.
The arguement that "if it is good enough for the airlines, it must be good for light aircraft" completely ignores the different environments. It is a horses for courses thing.
Written checklists have a lower propensity for error, but require more "heads-in" time. Mnenomic checks may lead to a higher chance for error, but are less distracting. Post-action checklists (the "scan then check" system) require more time to complete, and thus greater flightdeck time managment.
So with light, single pilot, aircraft where the consequences of an error are small, and the traffic is busy (as most operations are based on "see and aviod") the mnemonic check is appropriate. Forget to set the flaps in a 172, on 99% of runways, and you will hardly notice. Miss sighting another aircraft and you are in serious trouble.
Single pilot, complex aircraft (like a King Air) require a greater care in system settings, and so a written check becomes appropriate. The single pilot situation doesn't really allow for the longer post-action "scan and check" system, so an action check is a good compromise. Ticking off items as you go is faster than doing items by scan, and then checking them off a list, but you still have the memory protection of a written checklist.
Jet multi-crew, operating in an environment with positive trafic separation and with the flightdeck managment and co-ordination skills provided by multi-crew training, make the use of a post action "check and scan" checklist system appropriate. The big advantage of this, is that it allows for substantial cross checking. Each item can be done by one crew member, then checked by the other during the checklist. Double checks like that are not particularly relevent in single pilot situations. (Yes, I know checking something again in single pilot ops is always good, practically however when you miss something the first time the presupposition that you have completed that item can cause you to perform a false second check.)
My two cents anyway.
[This message has been edited by Checkboard (edited 04 April 2001).]