How about the complainers have to pay for Google's time
If the companies making these take down noticed had to pay google a refundable bond per notice then it would
1) Make the spammers pay for google to employ more people to check out these claims before actioning
2) Discourage notice spam
At the moment this system can remove a websites net presence on the say so of no one at all, there should be balance and a cost associated with wasting people's time for bogus claims without haing to go to court. After all the spammers are avoiding legal costs why not the defendants
Once the system settled down then it would reduce waiting time( more staff handling notices paid for by the spammers) and remove the idea that spamming these notices was cost effective. Eventually Google would only have to deal with real IP infringement.