So, commodity producers are not necessarily strongly correlated to the commodities they produce. See gold, for a striking example. Gold producers are more a spread trade between gold and inputs like oil.
Managed futures make some sense. It seems handwave-y to say that Canada's index is commodity-tilted and therefore correlated with a managed futures or commodity strategy. I haven't seen evidence to suggest that the TSX is highly correlated to commodities (the correlation to S&P 500 is much higher--why invest in US stocks?). Claymore used to have a brochure that demonstrated the effect of added MF to a stock/bond portfolio on volatility and returns that was pretty compelling. Unfortunately, iShares has sanitized any of that helpful literature from Claymore's products. Beyond that, there is plenty of literature exploring the value of managed futures strategies. I don't think it's a slam dunk to dismiss it as an asset class.
(side note: I've decided I'm not happy about iShares' acquisition of Claymore)
My biggest concern is that I don't feel happy with the products I've seen. To me, CBR has the highest potential of making it into my portfolio, but I'm not fully convinced by this product, and the iShare's takeover brings some uncertainty.