load sharing default routes vs rpm probe and ip monitor

I was kind of baffled by a S2J translation of two seperate default routes that  combined into one.. Having two with seperate preferences was intended to work with track-ip, but now I'm not sure what it will do. 

ScreenOS

-------------

set route 0.0.0.0/0 interface ethernet2/6 gateway 2.2.2.2 preference 25
set route 0.0.0.0/0 interface ethernet1/4 gateway 1.1.1.1 preference 15

JUNOS translation (doesn't care about interfaces now, that I get)

-----------

route 0.0.0.0/0 {
next-hop [ 1.1.1.1 2.2.2.2 ];
preference 15;
}

From what I read this is prefix IP round robin load sharing but ... what does that mean exactly?  http://forums.juniper.net/t5/SRX-Services-Gateway/default-route-with-two-next-hop/td-p/28214

I only want to use next-hop 1.1.1.1 unless if its completely down .. to which I learned I can do with rpm probe and ip monitor .. https://kb.juniper.net/InfoCenter/index?page=content&id=KB22052&actp=search

... but doesn't it need the default routes to be there as well? Am I thinking too hard about this, or am I completely off the mark here? Thanks for any help!

(addition)

Is it perhaps this?

route 0.0.0.0/0 {
    qualified-next-hop 1.1.1.1 {
        preference 15;
    }
    qualified-next-hop 2.2.2.2 {
        preference 25;
    }
}