Hi Taz that's a risk assessment you have to calculate in relation to your wares and the desirability of those wares in those areas you block.
I have had probably only about 5 in 1000 sales go to Asia in the past and I expect that to diminish due to my current wares.
I do not like blocking a large mass of potential buyers but in my case the present tedium of still receiving up to 15 Chinese e-mails a night since it happened and the possibilites of it turning nasty and expensive as it did in Suthrnjewl's case is enough for me to act in this way.