Law departments can share in benchmarking surveys nearly all of their metrics without concern for harming their company. Spending, staffing, matter loads and other data does not yield anyone a competitive advantage so long as the data is aggregated, normalized and anonymous (See my post of Oct. 17, 2005 that urges general counsel to take part in surveys.). I would argue that even if you disclosed this information to your arch-rival, your competitor cannot do anything nefarious with it.
This is far from saying that all information can be disclosed without repercussions. For example, amounts paid in settlement or settlement strategy are highly confidential. So are amounts set as reserves on individual cases. A practice of registering patents in different corporate names should be kept quiet as well as negotiating positions for basic contracts, such as terms and conditions. Some trends in lawsuits should never see the light of day any more than should specifics about what is spent on certain law firms.