It seems to me Radhakrishnan's Giitaa might be one of the best translations/commentaries I'll ever read. For instance, for XIII 12, he gives both Shankara's (anaadimat param) and Raamaanuja's (anaadi matparam) reading of 'anaadimatparam (in devanaagarii written as one continuous sequence) brahma':
http://www.flickr.com/photos/66867356@N02/7560460532/ R. himself seems to prefer Shankara's reading (anaadimat param)... In Shankara's reading, -mat is a (redundant) suffix meaning 'having' (no-beginning), because 'anaadi' as a *bahuvriihi* already has the meaning 'having'. As we recall it, Shankara explains that redundant -mat "away" as a verse filler(?), or somesuch... In Raamaanuja's reading 'mat-' is the "compound" form of 'my, of me', etc.
