CS solves some captcha CB can't solve (how I set that up, CB first and CS second) I just run GSA SER for a few hours.
Captcha status in SER is 3868|1353. Now I don't know the rate of which CS solves the remaining "difficult" captchas right, but as I watched it, it does a few correctly.
As I own both licenses, I guess it doesn't hurt. I have the CPU cycles anyway.
If you run SEO tools 24/7, it's only about time when you'll get back what you invest in both tools. Just pick your solution, either one or both.
At $77, CS only needs to solve about 51k captchas (assuming cheap $1.5/k rate) before you break even. I have passed that a long time ago.