re: my only concern
I haven't researched this, but last time I looked at it (a while ago) I understood that reprocessing pebbles was difficult. Of course, the silver lining to that is that it makes illegal diversion of materials and proliferation equally difficult.
The home page of the South African reactor project can be found here.
I won't say pebble bed is a cure-all for nuclear power, but we have to come up with something that works and start building reactors. This would be a good idea for helping wean us off of foreign oil even if nobody had ever heard of global warming.