They're actually designed to be used together. I've not used the heel-toe (on our bikes - had one years ago on my first bike) but would love to have a go on someone else's before buying one for myself given the price.
There's been some complaints that people can't adequately fit their boot between the heel & toe ends. Some people have modified them, most notibly by cutting the hell section shorter and bending it out slightly.
Oh, it stops the toe of your left shoe getting all marked up by the gearchange too.. if you're silly enough to wear dressy boots on the bike.
Hope that helps
Matt
