The object is to only cut the roots in about 3 places and only the outer roots. If we are talking about a 6" diameter pot, cutting 3/4" deep is plenty.I did not know that I could do that. I thought slicing through the roots would kill the plant. So I will remember that for next year. I live in northern Minnesota, and just buy tomato and pepper plants from the garden store. My pepper plants have not grown well in many years, and I always suspected they were root bound when I bought them. That is why I was looking at the soil blockers - to avoid plants that were root bound.
I start all my plants from seeds because the local stores do not carry the varieties that I need. I have a short growing season so the longer growing season plants that the local stores tend to carry won't work for me.
For a short cool season bell pepper, I grow King Arthur bell peppers. They do really good early on and in the fall but slow down during the hottest part of the summer. I have also been able to grow them in pots for peppers during the winter.
Good luck.