I can't overstate how much more productive I am with this tool. I wish the native file managers were anywhere near this good so I could have a high-quality experience on any given machine without having to install additional software.
As for open source - this one is, but it's written in delphi (pascal?) which makes it hard to contribute. Then again, it works well, so not sure what to contribute anyway.
Yes, I even have a copy of the Windows version of the original Norton Commander.
I used version 2.0 of NC in DOS 3 and version 3 in DOS 5.
I still miss the embedded viewing with Ctrl-Q that midnight commander is missing.
And I still prefer NC over TC, because it was so consistent.
I find the newer ones (especially total commander) much better than nc/mc.
Most TC fans I know are Russian, and most Russians I know are TC fans.
I really wish TC was open source so it was more actively developed.
[0] http://www.ghisler.com/