Do you still get spam? I didn't think it was a problem any more. I have been thinking about the next version of spam protection since presumably spammers will figure it out at some point, but for now, hiddeninput and badbehavior block everything quite nicely.
On my blog, I estimate that those two block 99.98% of the spam. I got the first false positive the other day (due to the bayesian filter) because someone used a handful of highly ranking words, but they got a notification it had been moderated, and the next time I logged in, I marked it as non-spam.
The wordpress plugin looks good, and contains some elements of what I have been thinking about. And I applaud removing the captcha - those don't really work, except for trivial spammers, and annoy users.
A simpler version of hiddeninput that I wrote on my company's contact page also has almost a 100% rate, and the number of spam attempts is much higher, a couple hundred a day are blocked. It's success rate is somewhere around 99.99%
If you don't have a decimal point on your accuracy percentage, it isn't worth talking about. For example, a webhost that boasts it is up 99% of the time, means that it is down 8 hours every month. Even at 99.9% it still is unavailable 5 minutes a month. I wouldn't accept a provider that offered those statistics. Once you get to "five nines", you are getting good. 26 seconds a month at the maximum is a more reasonable number.
For spam blocking, take my company web page, it has received ~25000 spam attempts in the last two months. If I had a 99% accurate filter, I would have gotten 250 spams in my inbox - ick.
My email filter for all of my personal email is 99.7% accurate, which is too low in my opinion.