Good point about the drippings staying inside the drum, with a strip rolled to the inside of the drum, but I wonder if rain water could get inside it? Wouldn't rolling the strip to fit the outside be better? Just asking, since I don't know the answer. I think WSM's have the problem of rainwater getting in since the lid fits inside the lip of the middle section.
I made a midi UDS some time and love it. It is a great size for 2 folks, but can handle a fair amount if you need to cook for more people. I did 2 8# pork butts for a party once, but have not pushed it to its limits to see how much food it can cook.
Some pics of my midi UDS build
I think I ended up with racks at 3", 8", and 15" from the top of the drum. In retrospect, I wouldn't worry about beer-can chix so much, because i think they are too much of a hassle now - would just spatchcock. I also would not add risers to all of the intakes, just one. And I would probably go with bigger intakes as well.
Have fun with your build. You're going to end up with a great cooker!