Looks good. Can't wait to see how it performs.
I am shooting for average performance (75-79% real world efficiency). I knew of some ways to improve performance but chose the path of least financial resistance. The big door and firebox might lower performance.
Things I've learned,
* the amount and weight of materials is daunting
* always use straight bricks - you can cut full bricks in half when you need splits, avoid slanted bricks (trouble)
* refractory mortar isn't a bonding agent - it is used to close gaps between 2 bricks so use as little as possible to accomplish this
or else you will be wasting $ (it is expensive)
* don't use 2X lumber for making slab forms (base, firebox floor, and caps) instead use plywood - line the plywood with plastic such that there are no wrinkles (2X lumber is often untrue and wastes $ because it is taller thus more refractory cement)
* if building a contraflow don't freak out while assembling the side channels being so flimsy - you'll lock them in place later - also the side channels are a repeating brick pattern - that is rows 1=3=5=7-etc & 2=4=6=8=etc... If you freelance and just build these by eye when you get to the top your refractory concrete caps probably won't fit - stick to the numbers.
Things I wish I had done,
* put wire mesh in the forms before adding refractory concrete (adds strength, could allow you to use less refractory concrete if desired)
* made an eco-box, i.e. a door and firebrick with air channels - this is a door that has channels for air which flows through it into the firebrick channels thus providing 'better' air to the burning fire which raises efficiency
* rebar vertically and horizontally embedded in the outer layer of the MH (earthquake protection), costs little
* set up vertical and horizontal plumb strings instead of relying on eye/feel