I watched the dterm video, and it looks interesting, but the lack of an apparent scrollback (as soon as I type a different command, the previous output is gone) would bug me. (Plus, does it support history, including search, etc?)
I'm using TotalTerminal - it's not context aware, but it's easier for me to launch it with Ctrl-` than to open a new virgin terminal whenever I need to do something really quick.
The only real win for dterm is the context-aware factor, but I find it to be a big-enough win that I keep it around. If you just need a quick virgin window and are using iterm2 (as you should be) then you can go into Prefs > Keys and set the global hot key toggle and then select the 'hotkey toggles a dedicated window with profile' to get a dterm-like overlay window that is a real terminal session.
I'm using TotalTerminal - it's not context aware, but it's easier for me to launch it with Ctrl-` than to open a new virgin terminal whenever I need to do something really quick.