A fair number of RNAV/GPS approaches here in the US have LNAV mins that are lower than the LNAV/VNAV mins. I've speculated as to why that is, but haven't seen a reference that either confirms or refutes my theory as to why that is. Anyone else believe it has to do with the obstacle clearance plane between the "on glidepath" at DA and the runway versus that of the "at the MAP at MDA?"