Thanks Andrew. Your experiment has me impatient to try a brew using no esky or pump, just the kettle and, 'mash sock.' Ross reckons I can get away with curtain material so will order some grain and should be able to do a brew on Wednesday. Thanks to you I'll probably hit the strike temp first up!
A lot of possible disadvantages to mashing thin have already been refuted thanks to Andrew so I thought it might be interesting to write down a few of the advantages. These might quickly tempt FNQ into having a bash at AG - lol. I'm sort of focussed off the original method which involved a pump so I hope James doesn't mind me continuing my possible hijack by just writing down the advantages of the sock method.
The advantages I've written down are not necessarily in order of importance. If anyone has any others they can see it would be great to hear them. Many of the below will not seem very important to experienced brewers but when they cast their mind back they'll certainly remember that a few things that seem so simple now such as building a mash tun, can be quite daunting when you're starting out.
Some Advantages of the Kettle and Mash Sock Method
1. Little Equipment Required: Only extras needed for those doing K&K are a kettle, a mash sock, thermometer and heat source. (Have not included chiller due to other methods of cooling being available.)
2. Excellent Temperature Control: Temperature of the mash is easily controlled by turning on and off heat source - something difficult to do with an esky. This means maintaining mash temp., multi-rest mashing and raising temp. for mash out are all easy to acheive. Temperature is also more stable due to larger volume.
3. Simple Quick Cleaning: Empty mash sock. Rinse and wash in washing machine. No cleaning of syphon and other vessel to vessel hoses and fittings.
4. Space-saving: Storage space approximately one-third of 3 vessel brewing. Working space whilst brewing is similiarly reduced.
5. Ergonomic: Brewing operations can be at at waist level.
6. Less 'Active' Time Required: Whilst the mash may still go for 90 minutes, during that 90 minutes all that is required is the occassional stir and temperature check/maintenance. No fly sparging or heating up water to correct temp for first and second sparges.
7. Kettle Size is Large Enough: From bigfridge's post above, we can see that a 50 lt kettle will handle a mash of quite big beers.
8. Simple Quick Set-Up: Self-explanatory.
9. One Volume and Temperature Calculation: Big advantage for new AG'ers.
10. Low Knowledge & Concentration Levels Required: The above method can be done without a lot of prior reading etc. The simplicity of the method also means the mash requires far less concentration. In your first few brews, heating different volumes of water to various temperatures that are ready on time can be spectacularly easy to stuff up. This should be simple but I know many are initially caught out on this and it stresses them out.
Better go now and write a PM to James apologising for all my long posts to his thread.

PP
P.S. Wobbly, sorry I can't help with any of your questions but my knowledge is a bit limited when it comes to pumps, re-circulation etc.