I totally disagree.
Going by your logic, a 24" Full HD should show picture even better than a 32" but it does not. I've compared against various sizes, brands, showrooms and lighting conditions. What you're saying is more of what's written in the book. I'm saying from my practical experience. I've owned my TV for more than an year and have watched different resolution movies/programs and know what I'm talking about. I own Hathway SD at home. Most of the showrooms have TS, Airtel, D2H. I've always found the picture quality of my TV inferior to what I've observed at showrooms (under your extreme lighting). Per your explanation, it should be the other way round. It's just the 720p movie that I'm comparing everything against.
Going by your lighting condition explanation, I could just laugh. Showrooms certainly does have more lighting than homes but you'd agree that they keep their TV sets tuned (colors, contrast, sharpness, brightness) in such a way that they look the best even under extreme lighting. Just a marketing strategy. At home, we customize TVs to look best under home lighting. May be you should really download a 1080p movie and watch it on your TV and than see the difference.
And 1080i or 1080p is essentially the same except the way they are transmitted to receiver. i is for interlaced and p for progressive scan. If you carefully read through TS and D2H websites, you'll see TS uses 1080i and D2H uses 1080p. i uses less bandwidth because it sends half of the actual image (even and odd numbered lines (of the total 1080 lines) per frame) but p sends full image in every frame transmitted but requires more bandwidth. i is an older technology and p is the latest one. Do a little bit research before you write something.