I like your shipping/setup system and the mattress generally. I sleep very well on it. But it's hard to sit on, and I think the top feels a little squishy. When I sit near the edge, with feet on the floor, I feel I'm going to slide off the edge, although I never do. This is an essential tradeoff of the type of foam you use. If it were stiff enough to sit on, it would be too uncomfortable to sleep on. The only type of foam that could conceivably achieve that compromise is thermal foam, which you have chosen not to use.
I also wonder how long this mattress will last. It is not even a little too hard. I fear it may turn too soft too quickly.
After having a waterbed for over 30 years, I need to get used to a different style of bed. So far I am VERY pleased with the T&N mattress.... It does tend to slide around on the platform though.
My son's guest room has a T&N. I found it very comfortable, and decided to purchase one myself. I'm a little disappointed with mine. After 3 weeks, it is already making an impression in the mattress. Disappointing!