VAssistX.SelectionToggleLineComment has two problems.
1) It only recognizes // at start of line. If there is already an indented // in a line, it will not uncomment the line, but will instead add an extra // at front of line, resulting in something like this:
// //puppy.jump();
Same thing happens when pressing the / key, which is enabled by checking "Surround selection on / * ( { and #". Both Visual Studio and ReSharper will uncomment lines even if // is indented.
2) It doesn't comment the current line if nothing is selected. Both Visual Studio and ReSharper comment current line if nothing is selected.
I would like to avoid using Visual Studio's line comment because it doesn't support toggling with the same shortcut key.