STI factory or aftermarket? STI's previous comments in this thread didn't seem particularly interested in the RMR.
There are a number of outfits offering to fit the Trijicon RMR Adapter Plate to a 1911/2011 slide. Vulcan Machine Werks
has been mentioned previously, and they have a nice Staccato package deal, as well as Primary Machine (which has coating options similar to the factory finish).
One of the benefits of going with the Trijicon Adapter Plate vice the DUO system has been getting the RMR/SRO to sit much lower. The CHPWS plate also seems like an upgrade, as the factory sights are quite tall to co-witness with the DPP. A thinner plate is also welcomed...the RMR/SRO sits quite high on the DUO model...