Oh yes, there are definite downsides. There are plenty of sites that won't show you anything. I've taken the tact that there is more on the net than I could possibly view in a million lifetimes and just move on. I could see some people taking exception here. And yes, I don't bother with google's captcha, since if that shows up, it'll most likely never work, even if you keep trying. Some of the others will let you pass after one successful test. I don't find tor to be too slow though.