Hey, me again

I have ditched the Specialized idea of a bike and looking at Treks and Giants. For Trek there is either the 4500 or the lower 4300. I know the components on the 4500 are somewhat better but im worried about the forks.
Trek 4500 Fork
RockShox Dart 3 w/preload, lockout, alloy steerer, 100mm
http://www.trekbikes.com/ca/en/bikes...4_series/4500/
Trek 4300 Fork
RST Gila T8 w/preload, 100mm
http://www.trekbikes.com/ca/en/bikes...4_series/4300/
Which one is better or worth the extra money? Could you talk about experience with either one. Is there a big difference?