Several times in the past few months, I've begun the painful yet sometimes enjoyable process of finding free software to replace some of my existing expensive proprietary software.  I downloaded and installed OpenOffice to replace Microsoft Office.  I considered giving Ubuntu another shot.  I tried a couple Matlab clones. 

And here's the conclusion I've reached:  Unless there's a specific negative reason why you want to switch to a different program that does the same thing (e.g. "I hate how it always does this" or "I can't get it to do what I want"), other than the fact that it's free and not made by a big faceless software company, it's not worth the trouble because you'll end up spending all your time trying to get the replacement software to perform the same functions as the replaced software.  As much as I'd like that to not be true, it just can't be avoided.  If you know how to use your software and it does what you want, there's no reason to switch.