Using plugins, a block of code can be commented or uncommented in Vim using the command
gc. Similar capability to toggle comments is available in Vrapper, but only in the language specific addons.
For example, if you are working with Eclipse CDT (C/C++), then install the Vrapper - C/C++ Extensions plugin to get this capability.
Tried with: Vrapper 0.54.0, Eclipse CDT 4.4.2 and Ubuntu 14.04