Pros
Most companies do not welcome you back with open arms after you leave. Uniquely Tresys, this company welcomed me back with open arms and without prejudice. I left for a position that wasn't available at Tresys and I returned because although I had loved the new job, I found their culture click-ish and mid-level management interactions toxic. Tresys offered me a position that is challenging and rewarding. They are flexible, respectful, and give me the space I needed to do my work well. The people on my projects are highly technical, skilled communicators, creative problem solvers, generous collaborators, and the list goes on. Great group of people! Also after 60 - 70 hours work week at my other job, the work life balance that has always been available at Tresys is truly a nice way to come home.
Cons
Since I've been back and in my current position, there's not much that has been a negative for me. I'm still too happy with being surrounded by people who makes sense to me that I haven't really focused on the cons.