I have a Expedition Asym Classic and while the tarp is small, I have yet to get wet under it as long as I tie it down per the instructions for bad weather on the HH web site. There is no place to actually sit under the tarp so I only use it when I need to really lighten my load.
I can see where headroom is an issue especially for someone taller than my 5' 2". I have a classic entry to therefore don't use my HH to sit up in but there is an answer for those who want to. This is a link to one of the forum vendors. http://www.2qzqhammockhanger.com/index.html
They can modify your HH so you can unzip the bug screen and I believe even disconnect the ridge line just so you can sit in it if you want. I am sending my HH off over the winter for the zipper mod #4 just to add versatility to it.