There is finally another open source decompiler on the market! Metasm (http://metasm.cr0.org/) has released a C decompiler module for its assembly manipulation suite. Although I had heard of it before, I was not terribly familiar with this toolsuite. So, I will be looking into this in the near future to learn what worked well in what they did and what I can improve upon.
IDA .sig format has some good progress. Need to get a block of time to finish it though.