OP, what do you expect of a OCR solution? ... if you want most captchas solved you need to be running OCR/Captcha Breaker as solver 1, and then pass all unsolved to human Captcha solving services, otherwise you're leaving all those links on the table. Yes it costs money... that's how this works.
Regarding plummeting of solve rates for SER ..... reCaptcha (google) has introduced new format. It looks the same to the naked eye, but the coding is completely different, and it was designed to fuck up all OCR solutions as google is well aware of these operations bypassing their anti-spam measures. All OCRs are currently unable to to process it besides CaptchaTronix (not affiliated, just a guy who makes a full time living selling links so needs to know this shit inside out). EVE, Spamvilla, and Captcha Breakers/SER own internal attempts to crack reCaptcha are all screwed for the last 2 weeks. They know the issue, they just can't figure it out. The Spamvilla developer told me it would be a few days to figure out... its been over a week. Same with EVE. That's the reason for solve rates down huge percentages using these services and CB/SER attempts to crack them.... they cannot even attempt to solve the new reCaptchas.
also I hope you guys realize , "solve" as reported by any OCR including SER internal/captcha breaker, does not mean actually solved.... especially when referring to reCaptchas or any kind of complicated captcha type.... it means attempted. If you're not following up with human captcha solving, or at the very least doing multiple solve attempts, chances are you're leaving tons of link on the table, and some of the best sites are protected with reCaptcha, so take that under consideration.
Best.