@Isabelle-you don't need a freestyle specific boot; you need a boot that fits. Most every freestyle boot is nothing but a painted normal boot (the new Lange's are exactly this). They fit great, which is why they are successful, not because there is anything specifically freestyle about them.
Some companies, like us, have actual shock absorbing properties in our freeski boots, but at the end of the day the boot that fits is the boot that works for your foot shape, weight, and flexibility.