Sorry to start a thread on this, but I think #I must (seeing some of the posts here).
Please, any system which attempts to keep the metre is unacceptable. I know it is the most widely used unit but that is not justification for keeping it. It is not based on humkan things, but off what was considered a "natural constant" at the time which, now irrelevent, leaves the metre with no footing, as it were, in the real world. It is an historical relic- please let's drop it forever.
Might I also remind everyone here that 1/1000000000 the distance light travels in a vacuum in a second is an 11.8 inch measure.