Hi Helene! I've been following your post, as I am just about to purchase a Liberator also! Hoping I love it. Now - I'm a novice - just been following the rocket stove posts for a couple of years - and particularly the ondol from Korea - so this is a question from a novice and I hope someone can jump in and help.
In my understanding, if you have the stove pipe winding through a bench - for heat - then that stove pipe should end up exiting the house at approximately bench level. This is the way ondol works. In fact for a few years I have been trying to duplicate it - with a lower level kitchen and fire smoke/heat winding its way under the floorboards of the house. If anyone at Permies has done this I would love to find out about it. I only have my Korean friends feeding me info about their homes and especially their older country houses.
If we were to create this system, why would we even need additional stovepipe going up out the roof? seems that is dividing the circulation and confusing the system. I've also sent this question to the good Liberator folks and look forward to their answer. Their instruction manual specifically calls for installation of a standard stovepipe going up. At this time I am not planning to add a bench or mass but just use the Liberator by itself but am interested in the possibilities.