Wow! Those are really some interesting arguments, I think one of my main problems with the iPad was traveling since I always took both devices with me (which makes your luggage heavier) and yeah on a plane I'll rather use the iPad mainly because of it's battery life but it's extra weight to carry. I travel across the ocean twice a year and I tend to stay more than a month each time, so I can't just leave my laptop.
I could totally see myself in an iMac + iPad environment, and I might do that in a far future since I recently built a high end Desktop PC. I was one of the first ones to have an iPad in my social circle, I got the first generation one a few months after it came out and I rapidly lost interest in it after the iOS4 update made it slower than my iPhone, making it even more redundant. It became old really quickly for me. I might want an iPad 5 if it seems promissing though. As I said, I really miss having a lightweight media device.