explo, I think doing the massive work that you mentioned and then putting everything on one China Solar stock gives quite some false sense of security of thinking the situation is under control. Of course you can find out about the balance sheet and crunch all the numbers available, but what do you do when one morning you find out that the CEO ran away with the companies money, or Chinese government accuses the CEO of corruption or there is a questionable deal announced or whatever and the stock opens gap down 50% (and that might even be justified then)? Your JASO did such a questionable deal before in 2011 already, so we can probably assume they are no saints. In fact, I know more Chinese stocks that frauded the investors than stocks that rewarded them. In german market there were something like 20 China stocks, each one of them turned out as fraud without exception. All of them got an audit opinion for at least one year before and the financial statements were not suspicious. For most the only "warning flag" was that they always traded at very low PEs that baffled investors and close to net cash. Some investors group even did site visits. In US the rate is a bit less, still there are quite many problematic ones and I am not sure if this could have been recognized in the financial statements before.
IMHO such a strategy might be ok for an old US stalwart, however prudent would be still far from it.
If you really judge results objectively, excluding currency effects, has such a strategy really improved the results compared to just take a basket of investing in TAN or taking just a few with good balance sheet and avoiding those with bad balance sheets? I guess you likely want a substantial return for taking such increased risk and for the additional work hours.