There seems to be lots of evidence that small/standard dietary quantities of soy are extremely safe - and it's really not surprising. I have eaten a range of soya products before without any particular restriction or symptoms/issues, and I know from personal experience plenty of people that either as Asians or vegetarians consume soya products regularly without harm.
The conclusion with this study though, as always, seems to focus on this somewhat weaker conclusion, thereby actually reinforcing my inclination not use a range of other vegan protein sources for my particular requirements. I am aiming to have elevated (not just acceptable) testosterone levels, and to consume about 150g of protein daily (not even close to an average diet I think, nor would the total energy input be, notwithstanding the obvious problems with counting protein and fibre as energy, my personal distaste for counting calories/kilojoules and its usually associated bizarre mindset that fitness is simply the opposite of fatness).
I am therefore still inclined not to focus on soy foods as my primary protein source, or to consume a soy protein supplement. If non-food protein supplementation proves unavoidable, I think pea protein may be the way to go for me, possibly mixed with small amounts of rice protein.
In any case, thanks very much for the stream of useful info. I won't be throwing away the tub of miso in the fridge or the 400g of soy bean pods left in the freezer. It is probable I will even buy a little more from time to time. The remaining skim milk powder is another story. I am not inclined to throw it away, give it away or consume it. I supposed I must ultimately do one of the three, but it won't be replaced.