A Quick Follow up, and my final opinion
Hello everyone, I have a quick update on what I think of level 9 walls. I've actually set a goal to finish all of mine, and they'll be completely done in one month and three weeks. I definitely see the benefit to upgrading them, for many reasons: the intimidation factor, 1000 more hit-points, and the cooler look. Would I now recommend everyone to get level 9 walls as a town hall 9? Well once again, yes and no. If you have the time to get at least 2-3 million gold a day, then i'd say it's more effective for the success of your base than upgrading to town hall 10. Although, if you can only raid 1 million gold or less per day, then i'd suggest you just upgrade to town hall 10. Ultimately, some say level 9 walls separate the "men" from the "boys", but I believe it separates the people have a lot of time from the people who don't.
In response to the question regarding level 10 walls as a town hall 9: I would not recommend upgrading to them. If you continue to raid a sum of 2-3 million gold per day, it'll take you almost a full year to accomplish, and infernos are definitely worth their time and gold: level 9 walls will fully satisfy your experience as a town hall 10, and you'll come to appreciate it as only 10-15% of all town hall 10s farmed them, let alone got them. :)