I have given Sketch a shot, and I feel like it's just as buggy, if not more buggy, than Fireworks.
I too rely on Fireworks every day for work and too experience the daily crashes. It really is a shame that the only product designed to for interactive work is filled with so many issues.
The only thing I can recommend (and i highly recommend you do) is enable autosave. I have mine set for 5 minute increments, so at most I lose 5 minutes worth of work. Just make sure you save the document before you start working on it, so there is an file to be autosaved.
It's really pathetic that I have to use such a hack of a fix just to make Fireworks functional. Hopefully either Adobe gets its act straight with Fireworks, or another product (like Sketch) comes along as a proper replacement.
@growing: Would you mind sharing how you enable and adjust the "auto save" settings? I see online that it can be edited directly from within a Preferences text file, as well as by using some type of command panel extension. But these seem like "back door" approaches. Is there a "front door" method to accessing this somewhat under-documented feature?
Unfortunately there is no "front door" approach from within the Fireworks App to enabling auto save. But it is a really easy fix from within the preferences file. Just do an "cmd + f" search from within the file for "autosave".
Here is the tutorial I used. Like in the tutorial, I left my auto save time increment at 5 minutes, which works perfectly for me.
I hope this helps and saves you some frustration as it has for me.