Dave - redex is primarily a top-end lubricant, with good detergent qualities, making it an effective carb (and inlet valve/cylinder/ring cleaner). Redex is typically used to regain compression by ungumming stuck rings.
Redex is not always available here in the desolate scandinavian wastes, and I often opt for ATF (automatic transmission fuel) which also has top-end lubricating capabilites as well as having detergent properties. In my experience, ATF is every bit as good as Redex, easier to get hold of and cheaper. So why do I use Redex? Because I used the stuff since I was a kid with his first bike - tradition dies hard.
I use both ATF and Redex as a 05-1% solution with every tankful.