Is there any chance you would be able to add a "Ask 3rd service to fill captchas" option to SER under the options pane? With SEREngines V2 I think it is going to become an essential option to use SER economically. My basic set up would be....
Captcha 1 - GSA CB
Captcha 2 - OCR
Captcha 3 - Human Solver
GSA CB would be for the bulk of the platforms, the OCR service would be for the contextual platforms and the human solver would be for the web 2.0s offered by SEREngines. This way the paid human solver option is only used on the most valuable platforms helping keep the price down.