Hi Ben,
I have to handle more Dohong first to be sure of this.
Like you have done because most of them are found in Dutch museums.
I have just added two additional, quite rare, Dayak knives to my collection site. It's the Piso Tongkeng of West Kalimantan and the Iban Lungat.
http://www.kampungnet.com.sg/modules...view_album.php
Michael