This will NOT give you static IP Addresses as the next time you power up the router it will most likely assign different addresses as I has now forgotten the previous lease.
Are you trying to say that the router loses its DHCP Range every time it is rebooted? That's no true! It retains whatever was last set as the DHCP Range by the user, just like any other parameters.
Any IPs outside this Range can be employed as static IPs by various means, e.g. fixing at the PC or assigning to a given MAC, which is essentially all that Address Reservation does. The IPs outside the Range are not issued by the DHCP, by definition, so cannot be forgotten.
I do agree that using IPs outside the Range is not the best way to achieve static IPs; using Address Reservation is far superior, easier, tailor-made and does not depend on messing about with PCs settings.
1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 20 Meg WBC