Springfield Armory 1911

Was wasting time (I mean doing research) at a local gun shop and I looked at a http://www.springfield-armory.com/products/1911-trp-45-acp/#PC9105L  I had not seen a 1911 without a barrel bushing and with a full length guide rod before, I was wondering what the benefit of such a system is.  The trigger on this particular pistol was very nice for an out of the box pistol.

thanks