The trend chart for OCA cf. RYM may be more in OCA's favour?
I had also gradually diversified out of my top heavy holding in SUM into OCA (& ARV) - and steeled myself to add a small extra holding during last years low point. I had previously diversified into SUM from RYM, and had been forced to quit MET and add to other retirement holdings. So for me diversification has had a neutral cost. My investment in the sector in general over the long term has outperformed though.