probably a little late to help on your decision.
i have had the nz6000 now going on the 2nd winter. we decided on this fireplace as a compromise, my wife wanted a fireplace for the ambiance and i wanted a wood burner for the heat. we installed it the February of 2010 in a new construction 2900 sq-ft ranch open floor plan with 9ft and cathedral ceilings. we have air brought in from the outside to feed the fire only(combustion air)thru a aluminum duct pipe that needed to be insulated to prevent condensation due to the warmer air in the basement(pipe is about 15 ft long) . i installed the blower in the basement so it would pull the air in the basement up around the fireplace and back out to the first floor then back down to the basement to recirculate.(.i couldn't see the benefit of bringing cold outside air in to circulate and cool the outside of the firebox.). the blower speed is controlled by rheostat on the wall next to the fireplace.
yes the hinges started to bend by oct.2010,... a newly designed hinge set was received in jan. 2011 and the doors have not sagged since.
yes , the nz6000 eats wood....it is the biggest firebox, it is a fireplace,with a metal shroud not a woodburner and it does put out all the heat i need to sit in shorts and t-shirts thru out the house all winter
! simple formula.. more wood... more heat..
yes this is a big unit and should be put in big rooms
yes, the glass gets dirty,especially with wet or unseasoned wood and always when the fire starts to go out. but if you dont want to clean 4 ft. of glass get a wood-burner or insert with solid doors. heck i had to clean the glass on every woodburner i've owned
yes , you only can go about 5-6 hours before you have to replenish the fire ( if you want see flames )but every morning when i get up after sleeping 8 hrs or so there are still plenty of coals left and all i do is put more wood in it , leave the doors cracked alittle for 10 or 15 minutes and it is back roaring again.
all i can say is this fireplace has been worth every penny...it has performed as we had hoped. it is a focal point in our house. visitors are amazed at the amount of heat it puts out and the beauty of it... both the wife and I are very happy with it