First of all, I love the ease of making custom hotkeys in TWS, and its customizability in general. I would love the addition of a Duplicate Line (or duplicate previous line) hotkey.
This is currently one of the only bells/whistles that the Eclipse IDE has that TWS does not in terms of the environment. I find it very useful.
Also, enabling Macros with a macro explorer to allow users to create their own hotkeys (rather than only being able to choose from built-in commands) would be another solution to this and other super-customized hotkeys.
Thanks for being so responsive to our requests! Love your team.