Hello Carl.

>   All the displays I've had experience with were bought surplus.

  Likewise!

> I think we needed some stupid cursor operation and so we went with the
> 8 line mode.

  Cursor or graphics perhaps?  I don't think 10-row mode (actually, 11-
row mode) causes problems with the cursor.

>  I believe one additional benefit from the additional driver chip
> however would be increased contrast do to the ability to use a higher
> (or is that lower?) multiplex rate.

  Yes, you do get a lower multiplex ratio if you use 8-character per
chip, single line mode.  Not much different if you use 11-row mode.
--
  Cheers,
        Paul B.