I understand there were a few incidents where either the SAS or RLI encountered armored units. And while fighting camps with populations in the low thousands, wouldn't it be fair to say there were at least vs. company sized engagements going on?

My thesis is roughly that the US should try learn several lessons from the Rhodesian Security Forces, mainly don't train whole brigades in COIN while neglecting HIC, keep cadre fresh from the fight, focus on Small unit tactics (like start printing 7-8 again), scouting is important to COIN, and again, scouting is important to COIN.