8) How does the counterguerrilla performance of 11ACR in Vietnam align with your argument?
My historical $.02 on the 11th ACR's performance is that it was able to more or less set its own operational parameters (within some CTZ guidance constraints, obviously). It was very successful in some areas, especially when it came to slowing infiltration from Cambodia in 1969, but was often more involved in route security than traditional COIN activities.

The division-level cavalry squadrons are, to me, a more interesting study, because their effectiveness or lack thereof in COIN was often tied directly to division operation methods. Comparing 1/4 Cav and 3/4 Cav might be interesting because they operated in more or less the same area (3/4 was roughly west of Saigon while 1/4 was roughly north although they shared a division AO boundary line) but had very different division operational frameworks (the 25th ID was considered to be more COIN-oriented than the 1st ID from about 1966 through 1968). In an aside, both divisions discovered the utility of mechanized infantry in COIN, and both also demonstrated the usefulness of tanks in such an environment. As jkm mentioned above, leadership is a huge factor in COIN, but armored forces have a utility in it that cannot be ignored.