Thanks for the responses.

ac777: As I mentioned I fly very little domestically so the upgrade aspect isn't of any appeal (and I long ago gave up believing that upgrade certificates were actually of any use--often crew seem to get the seats when I've been turned down). As I mentioned I qualify for Elite most years, not Super Elite. Typically I reach around 40,000 status miles. I do fly a great deal more than that but on tickets provided by others that typically do not earn points of any kind. There's no question of reaching 100,000 miles or status miles with AC. I find redemption with Aeroplan so arduous and laden with surcharges that my aim is to have as little to do with the scheme as possible, and from 2009 only to fly with Air Canada when forced, unless its demonstrably overwhelmingly to my benefit to continue with both scheme and airline.

Wouldn't there be any benefit to enrolling in the Lufthansa scheme and starting to collect Star Alliance points there, for instance?

What would the drawbacks be?

For OW airlines I'm currently enrolled with Qantas.

Thanks for any further thoughts. The various schemes are all so complicated it's hard to work out what's best.