Kudos to the developers of this plugin. Out of desperation and a deadline, I've just recently used FS Contact to replace all the forms on several new landing pages because the system provided in the landing page package were a total pain in the... , and wouldn't format properly due to css conflicts with the sites custom framework and css. I built and formatted 3 FS Contact forms in the time it took me to frustratingly mess around with one in the LP system which I gave up on.
Testing has demonstrated that the emailing system has worked flawlessly, the only exception being where I coded something in and made a typo in the code... i.e., my fault. Having said this, those who are experiencing problems should be looking at what they're doing, or not doing; the template or framework they're using it in and the web server's own idiosyncrasies. If you don't know what you're doing, you shouldn't be doing it, period!
Considering the effort these folks have put into creating this plugin and the cost, ;) the only suggestion I can make is to add a form cloning feature that allows one to duplicate a similar existing form, then modify it as needed.