The issue I have with "free tools" is that often times, they do one thing. Maybe one thing REALLY well…but one thing, nonetheless.
Coming from a Unix background, I really prefer the toolkit approach whereby I use a number of limited purpose tools rather than a one size fits all tool. That is not to say that I don't use EnCase or FTK but before they were around, there was dd, hexdump, etc., and, of course, Perl and Python and they were (and still are) pretty useful.
As a matter of fact, the nice thing about this is that you don't end up being bitten by the inevitable bugs that accompany new releases of commercial packages. There is nothing quite as frustrating as being in the middle of a case and finding that you have to "rollback" to a prior release of Package A because a feature upon which you were relying was "broken" in release X.
Greetings,
I'm a big fan of Linux style tools where I can pipeline information, or at least tie the tools together in a fairly automated manner. One of the things I'm really frustrated with on Windows at the moment is how little automation is available when using many of the tools. They are GUI driven and use incompatible file formats so the pipe-lining is left to the human. I do have issues with EnCase, but it does allow you to get a lot done within the environment. Fire off a bunch of tasks and walk away. (And hope it does not crash.)
-David