Is it appropriate? I don't see the problem, if people aren't interested, they can not read them or even downvote them.
You're asking a loaded question though. Louie will get a positive karma bias by being the first good optimal philanthropy article in a while. I think your article is probably better than his but might not rank as high, and it is even less likely to rank as high if submitted simultaneously with three other optimal philanthropy articles.
Waitingforgodel's article is good, but isn't written for a LW front page audience so it won't do well in terms of karma. Yours similarly doesn't do the intensive linkback to LW thing popularized by Eliezer.
Of course it doesn't really matter, since it doesn't sound like Roko will be judging based solely on LW karma score.
Several people have written articles on efficient charity -- throwawayaccount_1 has an excellent article hidden away in a comment, as does waitingforgodel. Multifoliaterose promises to write an article "at some point soon" ..., and louie has actually submitted an article to the main LW page.
What I'd like is for throwawayaccount_1, waitingforgodel and multifoliaterose to submit to the main LW articles page. People will read the articles, and hopefully vote more for better articles. Srticles not submitted to the main LW articles page are not eligible for the prize.
Note that it is hard for me to judge which article(s) will actually have the best effect in terms of causing people to make better decisions, so at least some empiricism is desirable. Yes, it isn't perfect, but if anyone has a better suggestion, I am all ears.