"...they are clearly no substitute for the simplicity of ordinary money."
Tim, the thing is with these local currency systems, none of them are meant to be a substitute for actual national money. No LETS system can take the place of money, and no local currency could ever replace the Pound either. All of these systems work alongside the "simple" national currency, you don't give up your bank account when you sign up for a LETS or accept some Brixton Pounds these are just additional tools we use to increase trade in our areas. I agree completely with you, we can't replace money using some mutual credit system and all sit around camp fires singing songs holding hands. (you simple can't buy a flatscreen TV or pay for a prescription with local currency, won't happen!) Of course not.
One correction for you, LETS are not as you describe, LETS permit you to value goods and services at market prices. So if you think your time as a house painter is valuable you can charge more than one unit per hour. LETS is more of a barter system made for trading, that is ....people without big cash to spend but who have stuff and want to exchange it with others locally. These type of systems are almost free to set up,
http://www.ces.org.za/ there is no big cost other than if you meet at the Pub once a week to discuss trading and see what others have, you still have to buy drinks! But look, I agree with you, if a guy has a new car every year and a great job with a pocket of cash...he's not going to participate in this stuff. It's not for everyone. A lot of mom's participate in these systems. Mom's who can't afford new toys each month so they bring in their old ones and often swap with other members, that is very popular.
Timebanks are the creature you speak of -- that values everyone's time equally. These are great system if it's right for you but certainly not suitable everyday commerce. This program is best for the aged or the people who just can't get a job for whatever reason. If you are 15yrs old and just can't get hired, you may want to consider a TB, or if you are 70 and can teach piano lessons to kids, a TB would be great for you, and then spend the credits and have the 15yr old to cut your grass. etc. In this case, the unit of time, is not valued by the marketplace, a TB unit is equal for all who participate and it's also NOT taxed, a contribution of time is a donation and not taxed, which also has a different benefit for those users. A transaction in LETS which is a sort of barter system, is a taxable event.
The Timebank is the very very basic starting point for those in the community with extra time. The LETS is a place for local to get together and swap cool old stuff, services or other goods.(barter). The local paper note, does neither of those, it encourages shoppers to use local stores over big chains. They are all called local currency but they all do something quite different. There is no way to say which would work in your area, if any, but they all operate alongside the national money. In no case is anyone saying these will take the place of the Pound or dollar, that does not happen. If your community is suffering, try one of these. Also they are not mutually exclusive, you can have all three operating at the same time alongside the Pound Sterling. Many communities do.