For real. The point you make is a good one, but involves different issues and a different set of policies. And I believe that a plan has an obligation to keep historical balances no matter how many changes in record providers, not that they do it properly. I do not think they have to keep daily balances, which gets into policies about using reasonable valuation dates and conventions for identifying the appropriate one to the extent the order does not specify (the valuation date that is nearest the desired date, immediately preceeding, or immediately following?).
Most of my clients can handle January 17, 1998 within legally acceptable tolerances (the answer is December 31, 1997). I am living the dream.