| I agree, but I'd also add semicolon and colon characters | to that list.

...and single, double quotation marks, parentheses, and dashes.

Double quotes aren't legal in URLs, so they're not an issue. But single quotes and hyphens are very common and I think it would be a very bad idea not to treat those as URL chars in all cases. I'm even bothered a little bit by question marks and exclamation points, but there is a workaround ([http://x.com/y? http://x.com/y?]), so I think it will be OK. I think colon and semicolon would be OK as well.