I've drooled over their website... Looks like an extremely well thought out and well built cooker. Definite "yes" on the insulated firebox but I'd skip the grill grate in the firebox option. You can buy a good dedicated grill for less than the price of the option. Hard to use the grill at the same time you're smoking without messing up the airflow. Stainless cooking grids would be great (grate?) but I imagine they're pricy. The stainless stacks with the ability to turn them as the wind changes looks like a great idea but I imagine the additional cost of materials and fabrication to be considerable. I'd spring for the adjustable plates.
It won't be a set and forget cooker... No stickburner is... but you should be able to get long burn times with a charcoal basket.