I do a lot of SQL processing using Excel as a UI that user's are
familiar with. In the past I used ADO in VBA to do most of this work,
but I found that this would cause errors on the Mac because they don't
have ADO. So now I use QueryTables instead - they still might not
work, but at least you can open the sheet without all sorts of errors.

Anyway, I've just written a query that pulls data from two systems. I
then run some basic formulas on the results. Now I need to upload the
results back to one of the two.

Is there any reason I can't use a QueryTable for this? I realize this
is a bit of abuse of the API, but is there any real problem I need to
know about?