I suspect that for the targeted recipients this gravity powered light would be ideal, particularly if one considers nomadic people, where a solar installation would probably be completely impractical.
What concerns me is the product's longevity.In comparison to a laboratory these devices are being targeted for use in a relatively very dirty environment. From the description I assume that there is some serious gearing up involved in order to spin the generator fast enough similarly to the spring powered devices. What material is being used for the bearings, gears etc?