If you have a reply to one of posts, and you want me to see that reply, it would be a good idea to comment directly on the post. My comments are open. I say this because I have actually found replies addressed to me on another blog buried within 50 to 100 comments. There may be others I did not find. It is not hard to post on my blog and your preferred blog.
If, on the other hand, you are not speaking directly to me, but only venting about my post, you can do that how you like. Although if you are simply talking to your fellows about one of my posts, it's probably a good idea not to begin the post with "Pvblivs:"