There are other factors that can cause a model to have a tendency to snap/spin or not recover. A wing warped with wash in, high wing loading, along with incorrect CG and sharp LE mentioned. Many WWII warbirds are bad for this mainly because of wing loading.
I had a Tweedy Birdy(.25 powered) and it came out a bit heavy since I used Coverite and painted it with SuperPoxy. It had the tendency to snap at low throttle when making approaches. Also a bit slow to recover from spins but never overrotated more than one turn when neutralized. Dead stick finialy did it in. Still have the plans and someday maybe I'll build another.
If you have a .60 size and it is in the 9+ lb range then you might expect to have spin recovery problems. I do not think that it will be a factor in the 2M Dirty Birdy as you have a much larger wing and the Renold's numbers work in your favor on the big birds.
PilotFrog