Cisco WAN :: 877 Default Route Using Track Command?

I have an 877 router which has a DSL WAN interface. The DSL service at this site is unreliable, so the company have purchased a separate 3G router to be used as a backup. This device maintains 3G connectivity at all times and has a static IP on the internal subnet (for arguments sake let's say 10.0.0.253).
 
What I want to do with the Cisco router is to track the DSL interface and if it is up, install a default route pointing to it. If it is down, I want the default route to be the 3G router.
 
I am thinking the best way to do this is to set up a track and then set 2 default routes; one which is installed if the tracking is up, the other has a higher admin distance and points to the 3G router and thus should only be used if the track is down. For example:
 
track 10 interface Dialer0 ip routing
delay down 30 up 30 
ip route 0.0.0.0 0.0.0.0 Dialer0 track 10 
ip route 0.0.0.0 0.0.0.0 10.0.0.253 100
 
Is this likely to work or is there a better way to do it?