Re: 2-piece blanks
If you want 2 piece rods, go for it. I know some people do prefer them. Some companies offer them, and if enough folks want 2 piece over 4 piece then more companies will make more of them. Lack of options in 2 piece rods just speaks to the market. I don't think I'll buy a 2 piece again. My understanding is that in the past ferrules created problematic flat spots but the technology has improved and helped correct this problem. Perhaps someone more knowledgeable can speak to it.
The slight weight difference is of zero concern to me, I don't worry about a weak spot as the ferrules are wrapped for strength (I believe some blank manufacturers say you don't need to wrap theirs anyways), and I really value the space saving on my garage storage shelf and in the back of my car. I can fit the rods, but like having the tubes take up less space. I find the longer tube of my bamboo rod annoying personally, but love the rod. I never found putting the rod together to be any kind of trouble when I get to the river.
In short, 4 piece rods might be problematic for you, but they aren't for me.