I think it's not polite, if you just want to show something cool you did you could create your own thread. You don't interrupt a street musicians and start playing in front of the crew just because you think you are a "better" artist or that your version of the song is cooler right? It's common courtesy.
On a side note, I looked at both codebases and even though I've already said that I wouldn't use either of them I have to say that I find rurbans to be somewhat messier and uglier so I have to disagree with you.
Your attitude may apply to some situations, but in general preliminary judgements kill innovation. Next time after reading your comment, someone somewhere may remain silent without showing off their art, and the world will be missing the next Copernicus, Gauss, Wozniak, Stroustrup.
If I have to choose between "polite" and "innovation", I choose "innovation" any time of day. This is the same kind of difference as to "diss" someone for no real reason as opposed to letting someone just be and "blossom" so they could share their enlightenment with everyone, and thus benefit us all.
Well, you know, there is a way to share your work without putting others down or being dismissive.
It's really valuable (and sometimes even enjoyable) for others to read (or even participate in) a conversation between two (or more) knowledgeable individuals who share their perspective and explain why they made the choices the made in their implementations (hint: here's where he could share some of their work!).
In fact, this is the polar opposite of that and it's just sad.
I feel like rurban's comment is more likely to prevent someone from showing off in the future. Like what's the point when someone is just going to drop by and say "Mine is better, <link>" and then peace out with no constructive discussion?
On a side note, I looked at both codebases and even though I've already said that I wouldn't use either of them I have to say that I find rurbans to be somewhat messier and uglier so I have to disagree with you.