A pivottables takes more memory than a sumproduct for the same data and
pivottable size. Besides, it is also much more sensetive to the chance
of corruption(Pivot and query table objects are much more sensetive to
corruption than simple formula's).

Another thing I forgot to mention is refreshing, which is manual with
pivottables but can be automatic with SUMPRODUCT. Also SUMPRODUCT has
less compatability issues (although this will not be a big issue) with
conversions to other products/platforms.

DM Unseen