Look it is true that Marx and Marxists think that Capitalism is an exploitative economic system just as was Feudalism to which even our good liberal friend Bradford would agree. The point of the LTOV is to show how exploitation can be measured at the level of the system as a whole. It is a general theory of price formation not a micro-theory of price selection (for that, Marx thought classical and perhaps would have thought neoclassical theory was just fine i.e., at the level of the individual subjective evaluation of alternative choices which are related to market prices established via the forces of supply and demand). To defeat the LTOV one needs to demonstrate that capitalism is -not- a system of exploitation, by which it is meant that one class in virtue of their control over the bulk of societies productive assets does not control and appropriate the labour and creativity of those who have -in the main- only their labour power to sell. The LTOV simply attempts to allow some approximate quantification of that appropriation. To remark that there are normative dimensions to this project is simply make a trivially true observation that can in no way vitiate its claim to objectivity. Just as to remark on the normative dimensions of the neoclassical project since its inception, which any cursory glance at the history of the development of economic thought will show, does not in and of itself vitiate the neoclassical claim to objectivity or a science. The best one can do is show that for certain questions the normative dimensions of a project shut down or make the research program blind to certain phenomena. For example, if one is found of assuming the initial endowment- as my neoclassical friends are- it is an implicit claim that the present distribution of wealth is just and an explcit claim that any attempt to alter it is both non-Pareto optimal and inefficient. Notice that the critical silence entailed here is rather devastating but the neoclassical claim that it is objectively true that a redistribution of wealth would be non-Pareto optimal and inefficient may be correct when viewed through that lens. What Marx, and Marxists purport to demonstrate via deployment of the LTOV is what structures and allows for the reproduction of the hierarchical class divided reality of capitalist societies. The LTOV is integral to making the link between the phenomenal quantities of capitalist societies (eg profits, wages, productivity) and the conditions of possibility for those phenomenal forms (eg the social relations which supply the necessary and sufficient conditions for the phenomenal forms).
On a different note it is simply not true that the LTOV does a poor job at measuring and explaining empirical macroeconomic phenomena (see for example Shaikh http://homepage.newschool.edu/~AShaikh/labthvalue.pdf). Quite a part from whether or not you, Doug or Andy find it useful for the work you do is another matter. I suspect that given the work Andie does the LTOV has no particular use as Andie's project is about justice within the normative dimensions of liberal theory as to what is or is not fair. Exploitation within liberalism is only about policing exceptional behaviour vis-a-vis liberal norms not about undoing the normative foundations of liberal justice. And to get outside of the prison house of liberalism as the only normative benchmark one needs an alternative theory not just of how prices are formed but also, and most importantly, of what the normative basis of liberal societies are founded upon. What a remarkable contribution the LTOV makes in this regard.
Travis