Are you working for a competitor now? If so, might previous company have a game plan that really turns out unpleasant for you?
I'd have a hard time going back to a company that let me go recently. Maybe it is just age talking. If you're young(er), then it is probably worth the risk to go back for 10% more. That's something like 3% for each year you weren't there, and 4% to pay you back for inconveniences you went through due to there poor judgment.