On the Blog page the Reply option does not work on new posts. Clicking on Reply does nothing. You have to go in the post itself and then reply from there. As soon as the Blog post has at least one reply, the Reply option on the main page then works for that particular post, but not for other posts with no replies.
I'm afraid I'm not seeing any difference between posts without replies and posts with... They're both leading to the proper reply page. Can't you just post what your link points to, and what shows up in the end..? Blog homepage, or blog post's page..?
All right! Looks like that's another Pete bug... :P The link depends on what setting is enabled for Quick Reply, apparently. I'm guessing the quick reply boxes are open by default, in your regular forum topics..?